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Studies of metal-free carbon nanostructures prove effective in energy and environmental applications due to their molecular tunability and vast chemical space. Herein, we synthesize nitrogen-containing multi-walled carbon nanotubes (N-MWCNTs) via. acid-catalysed incorporation of 3, 4-diaminopyridine into multi-walled carbon nanotubes (MWCNTs), and demonstrating their efficacy in electrocatalytic hydrogen evolution reaction (HER) and semicarbazide (SCB) oxidation for energy and environmental waste management, respectively. Successful synthesis is further confirmed by analysis techniques, i.e. Fourier transform infrared (FTIR) spectral analysis shows the diminishing OH frequency around 3250 cm−1 in MWCNTs after functionalization and the formation of an O C–NH bond in N-MWCNTs at 1710 cm−1. X-ray diffraction (XRD) confirms the incorporation of N-species, while Raman spectroscopic analysis indicates an increase in the I D /I G ratio MWCNTs (∼1) to N-MWCNTs (∼1.25), suggesting more defective sites in the N-MWCNTs nanocomposite. X-ray photoelectron spectroscopy (XPS) reveals peaks at 399.38, 400.49, and 402.05 eV, attributed to pyridinic-N, aromatic amide-N, and protonated amine groups, respectively. N₂ adsorption-desorption studies shows a high Brunauer-Emmett-Teller (BET) surface area for N-MWCNTs (119.22 m2/g) compared to MWCNTs (74.94 m2/g). Linear sweep voltammetry (LSV) profiles demonstrate enhanced activity of N-MWCNTs for both HER and SCB oxidation at an ultralow potential of E = −0.55 V vs RHE at 10 mA/cm2, with a lower Tafel slope of 108 mV.dec−1. Moreover, the electrochemical sensing studies indicates on N-MWCNTs were demonstrating an efficient electron transfer to SCB with the lower detection limit of 0.004 μmol. This work provides carbon-based metal-free electrocatalysts for energy harvesting and environmental management. [Display omitted] • An easy way to synthesize N-MWCNTs nanocomposites was developed. • N-MWCNTs shows superior electrochemical activity and stability in semicarbazide and hydrogen evolution reactions than MWCNTs. • The presence of N in N-MWCNTs develops new sites for enhancing conductivity and electrochemical reactivity. [ABSTRACT FROM AUTHOR]

Creating innovative catalysts utilizing nonprecious metals for the electrocatalytic hydrogen evolution reaction (HER) poses a significant difficulty. We present a cobaloxime (Cox) complex having pyridine (2-Cox) and tetrafluorophenyl-thio-pyridine (4-Cox) functional groups, which contains a 4,4-Difluoro-4-bora-3a,4a-diaza-s-indacene (BODIPY) moiety. This combination serves as a catalyst for proton reduction and is immobilized onto reduced graphene oxide (rGO) by π–π stacking between the cobaloxime complex and rGO. Moreover, the unique complex's structures were determined through the application of ultraviolet–visible spectroscopy (UV–Vis), Fourier Transform Infrared spectroscopy (FT-IR), X-ray diffraction spectroscopy (XRD), and scanning electron microscopy (SEM). The electrocatalytic activity of the two rGO/2-Cox and rGO/4-Cox electrodes towards hydrogen (H 2) were examined under both alkaline and acidic conditions. The cobaloxime-modified rGO electrodes demonstrate superior electrocatalytic performance for the HER under acidic conditions compared to alkaline conditions. The overpotential at a current density of 10 mA cm−2 for rGO/2-Cox in 0.5 M H 2 SO 4 is −0.342 V, which is notably lower than the overpotential of rGO/4-Cox (−0.496 V). The Tafel slope for the rGO/2-Cox electrode in a 0.5 M H 2 SO 4 solution is 111 mV.dec−1, but for the rGO/4-Cox electrode it is 156 mVdec−1. This discrepancy suggests that the rGO/2-Cox electrode demonstrates better performance in the HER compared to the rGO/4-Cox electrode. • Two different BODIPY-cobaloxime complexes were synthesized. • These combinations are immobilized on reduced graphene oxide by π-π stacking. • The electrocatalytic activity of these structures towards hydrogen was studied. • 2-Cox structure exhibited superior electrocatalytic performance for HER. • These catalysts have the potential to be used in various energy applications. [ABSTRACT FROM AUTHOR]

The efficient and high-quality production for hydrogen through water electrolysis at high current densities is crucial for commercial utilization. However, the performance of existing hydrogen evolution reaction (HER) electrocatalysts is far from satisfactory. In this regard, we proposed a method to prepare Rh–Ni(OH) 2 catalyst based on Nickel foam (NF). The hydrolysis galvanic replacement of nickel boride with RhCl 3 led to produce a lattice contraction in Ni(OH) 2 due to the rigid pressure generated, resulting in outstanding HER performance at high current densities. It achieves an industrial current density of 500 mA cm−2 with an overpotential of 130 mV. Furthermore, at the industrially prefer temperature of 80 °C, only 67 mV overpotential is required. The catalyst also demonstrated exceptional stability, maintaining excellent performance even after a stability test of 100 days with a current density of 200 mA cm−2. Through Density-functional theory (DFT) calculations, Rh series reduced the hydrogen adsorption free energy. The electronic structure of Ni was improved by pretreatment with NaBH 4 , and then it reacted with Rh species, triggering the lattice contraction of Ni(OH) 2 , and the existence of this effect makes Rh play an active site role at the same time, and Ni also plays an auxiliary role in its role. The result is a highly efficient catalyst (Rh–Ni(OH) 2 /NF) for HER that achieves a current density of 500 mA cm−2 at only 130 mV and remains stable for three months under constant current conditions. [Display omitted] • Rh–Ni(OH) 2 on nickel foam boosts hydrogen production at high current densities. • Lattice contraction in Ni(OH) 2 due to Rh improves HER activity. • Achieves industrial current density with low overpotentials (130 mV at room temperature, 67 mV at 80 °C). • Exceptional Stability: Maintains performance even after a 3-month test. [ABSTRACT FROM AUTHOR]

Finding a novel material to substitute the existing noble metal catalysts for the hydrogen evolution reaction (HER) is essential for the further advancement of water electrolysis technology. Herein, we investigated the feasibility of using defect engineering to improve the hydrogen evolution reaction (HER) catalytic performance of WTeX (X = Se, S) materials in the 2H, 1 T, and 1 T′ phases. The results demonstrate that the introduction of defects significantly enhances WTeX monolayers' HER performance. As exemplary cases, the Gibbs free energy changes for 2H WTeSe with a Te vacancy (2H WTeSe–V Te) and 2H WTeS with a Te vacancy (2H WTeS–V Te) are 0.029 eV and −0.002 eV, respectively. It was found that the active sites in 2H WTeSe–V Te and 2H WTeS–V Te have a substantial number of empty anti-bonding states, which increases the bond strength between H and the catalyst, leading to exceptional catalytic performance. This work demonstrates the feasibility of defect-engineered WTeX structures as electrocatalysts and provides a reliable reference for the study of non-precious metal catalysts. • Defect introduction boosts HER performance, especially in 2H WTeX-V Te. • W atoms' 5d orbitals play a key role in enhanced HER in 2H WTeX-V Te structures. • Strong W–H bonding forms stable H adsorption, promoting the HER process. • 2H phases show concentrated charge transfer, outperforming 1 T and 1 T′ in HER. [ABSTRACT FROM AUTHOR]

The rise of MXenes and their derivatives, particularly two-dimensional (2D) transition metal borides (MBenes), marks a significant advancement in 2D nanomaterials. Their versatility has sparked great interest in various research fields, paving the way for their use in multiple applications such as energy storage. MBenes have desirable electrochemical and electrical properties, such as high electrical conductivity, making them highly effective catalysts for a variety of electrochemical reactions, including the oxygen reduction reaction (ORR), oxygen evolution reaction (OER), and hydrogen evolution reaction (HER). Therefore, this mini-review provides an overview of the current progress in the field of MBenes-based composite materials used as electrocatalysts for ORR, OER, HER, and water splitting. Moreover, this study examines both theoretical and experimental studies to identify the factors influencing the electrochemical properties of MBenes-based electrocatalysts, offering insights into improving and optimizing their catalytic activity and chemical stability. By addressing the complex interaction between MBenes and their electrochemical performance, this study serves as a valuable roadmap for researchers aiming to improve the efficiency and durability of MBenes-based electrocatalysts. [Display omitted] • 2D MBene nanostructures were reviewed for their electrocatalytic applications. The challenges and opportunities of MBenes in practical applications are summarized. The incorporated supercapacitor exhibits excellent electrochemical properties. MBene's role in composites is explained. [ABSTRACT FROM AUTHOR]

Solar saline water splitting is a promising approach to sustainable hydrogen production, harnessing abundant solar energy and the availability of brine resources, especially in the Atacama Desert. Bischofite salt (MgCl2·6H2O) has garnered significant attention due to its wide range of industrial applications. Efficient hydrogen production in arid or hyper arid locations using bischofite solutions is a novel and revolutionary idea. This work studied the electrochemical performance of Mn2O3 electrodes using a superposition model based on mixed potential theory and evaluated the superficial performance of this electrode in contact with a 0.5 M bischofite salt solution focusing on the hydrogen evolution reaction (HER) and oxygen reduction reaction (ORR) that occur during saline water splitting. The application of the non-linear superposition model provides valuable electrochemical kinetic parameters that complement the understanding of Mn2O3, this being one of the novelties of this work. [ABSTRACT FROM AUTHOR]

Anion exchange membrane (AEM) water electrolysers have shown their potential in green hydrogen production. One of the crucial tasks is to discover novel cost‐effective and sustainable electrocatalyst materials. In this study, a low‐cost Ni−S‐based catalyst for hydrogen evolution reaction was prepared via a simple electrodeposition process from a modified Watts bath recipe. Physical characterisation methods suggest this deposit film to be amorphous. Optimisation of the electrodeposition parameters of the NixSy catalyst was carried out using a rotating disk electrode setup. The optimised catalyst exhibited excellent catalytical performance in 1 M KOH on a microelectrode, with overpotentials of 41 mV, 111 mV and 202 mV at 10, 100 and 1000 mA cm−2 with Tafel slope of 67.9 mV dec−1 recorded at 333 K. Long‐term testing of the catalyst demonstrated steady performance over a 24 h period on microelectrode at 100 mA cm−2 with only 71 mV and 37 mV overpotential increase at 293 K and 333 K respectively. Full cell testing with the optimised NixSy as cathode and NiFe(OH)2 as anode showed 1.88 V after 1 h electrolysis at 500 mA cm−2 in 1 M KOH under 333 K with FAA‐3‐30 membrane. [ABSTRACT FROM AUTHOR]

Given the diminishing reserves of fossil fuels, the development of renewable alternative energy sources is of global importance. Photocatalytic hydrogen (H 2) evolution stands out as a promising and cost-effective method to harness sunlight for producing carbon-free H 2 fuel. Recently, two-dimensional (2D) covalent organic frameworks (COFs) have garnered considerable research interest in photocatalysis on account of their exceptional surface area and predictable assembly of diverse molecules with adjustable electronic properties. Herein, six 2D COFs are constructed by topologically assembling phosphorus-alkynyl functional moieties and benzene-based building units, including benzene (COF-1), triazine (COF-2), heptazine (COF-3), triphenyl-benzene (COF-4), triphenyl-triazine (COF-5), and triphenyl-heptazine (COF-6), employing first-principles calculations. Our computational results illustrate that the variation of benzene-based building units significantly regulates the electronic structures of COFs, all of which possess semiconductor properties with tunable bandgaps spanning from 1.56 to 2.56 eV. Of particular importance, COF-1, COF-2, COF-4, COF-5, and COF-6 can spontaneously stimulate the hydrogen evolution reaction (HER) under their own light-induced bias without the need for sacrificial agents and co-catalysts. Among them, COF-4 and COF-5 show the best HER activity without light-induced bias, with ΔG values of 0.02 and −0.01 eV, respectively, whose excellent photocatalytic performance can be ascribed to their appropriate electronic band structures, pronounced optical absorption, and low work functions. This finding offers profound insights for exploring other highly efficient HER photocatalysts. Synopsis: Phosphorus-alkynyl COFs (COF-1, 2, 4, 5, 6), featuring varied benzene-based units, can spontaneously initiate HER under light-induced bias, eliminating the reliance on sacrificial agents or co-catalysts. [Display omitted] • The 2D COFs are constructed by phosphorus-alkynyl moieties and benzene-based units. • Varying the benzene-based units notably modulates the electronic structures of COFs. • COF-1, 2, 4, 5, 6 can spontaneously initiate HER under their own light-induced bias. • COF-4, 5 show superior HER activity in the absence of light-induced bias. [ABSTRACT FROM AUTHOR]

Hydrogen, known for its high energy density and environmental benefits, serves as a prime substitute for fossil fuels. Nonetheless, the hydrogen evolution reaction (HER), essential in electrolysis, encounters challenges with slow kinetics and significant overpotential, which elevate costs and reduce efficiency. Thus, developing efficient electrocatalysts to reduce HER overpotential is vital to enhance hydrogen production efficiency and minimize energy consumption. Adjusting the electronic structure of transition metal oxides via elemental doping is a potent strategy to improve the effectiveness of electrocatalysts for hydrogen evolution. In this work, we synthesized a set of niobium‐doped tungsten oxides (Nbx‐W18O49) under anoxic conditions using a straightforward “one‐pot” solvothermal approach. After doping Nb, the oxygen vacancy content inside W18O49 was increased, which induced a synergistic effect with the active sites of tungsten. In acidic environments, the hydrogen evolution activity of the Nb0.6‐W18O49 electrocatalyst is second only by 20 wt % Pt/C. It attains a current density of −10 mA cm−2 at an overpotential of 102 mV. By comparison with W18O49, Nb0.4‐W18O49 and Nb0.5‐W18O49, Nb0.6‐W18O49 demonstrates a reduced charge transfer resistance, which significantly enhances its conductivity and the speed of electron movement across interfaces. Coupled with this feature are notably faster HER kinetics. Additionally, it exhibits excellent stability, meaning it maintains its performance and structural integrity over prolonged periods and under various operational conditions. This article provides a new perspective for discovering inexpensive and efficient hydrogen evolution electrocatalyst materials. [ABSTRACT FROM AUTHOR]

In the last few years, the development of effective electrocatalysts hold fascinating importance towards scalable green hydrogen (H2) and oxygen (O2) production has become an appealing area of research. A good number of iron‐based catalysts have been designed and synthesized which can mediate water splitting under mild conditions with minimum energy requirements. In this review, recent progress on iron‐based electrocatalysts focusing on Oxygen Evolution Reaction (OER), Hydrogen Evolution Reaction (HER), and Overall Water Splitting (OWS) are summarized. Tactical designing, targeted synthesis with electronic tuning, efficiency as well as durability are discussed here. The review is comprehensive and our target is to promote the development of highly efficient economical catalysts, to make their way from the laboratory to market by replacing noble metal‐based electrocatalysts. [ABSTRACT FROM AUTHOR]

Hydrogen production using the photocatalysis approach is considered a feasible option for achieving a sustainable future. In this work, we conducted a comprehensive investigation into the hydrogen evolution reaction (HER) performance of the XSeI monolayers (where X represents either Sb or Bi) using density functional theory (DFT) calculations. We simulate and optimize the structural properties of the 2D XSeI Janus monolayers in its H-phase, ensuring stability through cohesive energy and phonon analysis. For SbSeI, the computed cohesive energy is − 2.06 eV, and for BiSeI, it is − 2.14 eV. Subsequently, we explored the electronic characteristics, including density of states (DOS) and electronic band structure. The various machine learning (ML) models were integrated into our approach for predicting the band gap of Janus monolayers. Employing DFT calculations, we systematically examined the HER activity of the XSeI monolayers, assessing its responsiveness to doping, with a particular focus on Pt and Pd atoms. The calculated Gibbs free energy for Pd–SbSeI and Pd–BiSeI is 0.33 eV while for Pt–SbSeI and Pt–BiSeI, it is − 0.23 eV and − 0.21 eV, respectively. The study not only contributes insights into the fundamental electronic and catalytic properties of the XSeI monolayers but also investigate the potential for enhancing its hydrogen evolution performance through strategic doping strategies. The study demonstrates the stability and electronic properties of XSeI Janus monolayers using DFT calculations. Employing the random forest model, we predict the band gap at the HSE level for both Janus monolayers. We explored HER activity, finding promising results with Pt and Pd atom doping, especially for Pt-doped XSeI. [Display omitted] • We focused on pristine and doped XSeI (X = Sb, Bi) Janus monolayers in their H-phase. • ML models have the capability to predict the band gap of any Janus monolayer. • The examination of hydrogen evolution reaction (HER) activity within both pristine and doped Janus monolayers XSeI. • To explores the possibilities of improving their hydrogen evolution performance via strategic doping. [ABSTRACT FROM AUTHOR]

Facing with serious carbon emission issues, the production of green H2 from electrocatalytic hydrogen evolution reaction (HER) has received extensive research interest. Almost all kinds of noble metal phosphides (NMPs) consisting of Pt‐group elements (i.e., Ru, Rh, Pd, Os, Ir and Pt) are all highly active and pH‐universal electrocatalysts toward HER. In this review, the recent progress of NMP‐based HER electrocatalysts is summarized. It is further take typical examples for discussing important impact factors on the HER performance of NMPs, including crystalline phase, morphology, noble metal element and doping. Moreover, the synthesis and HER application of hybrid catalysts consisting of NMPs and other materials such as transition metal phosphides, oxides, sulfides and phosphates, carbon materials and noble metals is also reviewed. Reducing the use of noble metal is the key idea for NMP‐based hybrid electrocatalysts, while the expanded functionality and structure‐performance relationship are also noticed in this part. At last, the potential opportunities and challenges for this kind of highly active catalyst is discussed. [ABSTRACT FROM AUTHOR]

It is highly desirable to design efficient and stable hydrogen evolution reaction (HER) and oxygen evolution/reduction reaction (OER/ORR) electrocatalysts for the development of renewable energy technologies. Herein, density functional theory (DFT) calculations were conducted to systematically investigate a series of TMNxO4−x-HTT (TM = Fe, Co, Ni, Ru, Rh, Pd, Ir and Pt; HTT = hexahydroxy tetraazanaphthotetraphene) analogs of two-dimensional (2D) conductive metal-organic frameworks (MOFs) as potential electrocatalysts for the HER, OER and ORR. The thermodynamic and electrochemical stability simulations suggest that these designed catalysts are stable. Remarkably, CoO4-HTT, RhN3O1-HTT and IrN3O1-HTT are predicted to be the most promising catalysts for the HER, OER and ORR, respectively, surpassing the catalytic activity of corresponding benchmark catalysts. The volcano plots were established based on the scaling relationship of adsorption Gibbs free energy of intermediates. The results reveal that regulating combinations of metal active centers and local coordination environments could effectively balance the interaction strength between intermediates and catalysts, thus achieving optimal catalytic activity. Our findings not only opt for the promising HER/OER/ORR electrocatalysts but also guide the design of efficient electrocatalysts based on 2D MOFs materials. [ABSTRACT FROM AUTHOR]

[Display omitted] • The Pt 78 La 22 alloy particles are about 2–10 nm and well dispersed on carbon black. • Pt 78 La 22 /C with much superior electrocatalytic activity and stability for HER and MOR than Pt/C-JM. • La accelerates the water decomposition and desorption of *OH at the Pt sites, thus increasing the catalytic property for HER. • In-situ FTIR have shown that Pt 78 La 22 /C can increase the breaking rate of C O bonds and enhance MOR performance. • The coupling of HER and MOR enables hydrogen production at low potentials. The development of clean energy solutions, such as fuel cells and hydrogen energy, is crucial for addressing the global energy shortage. Platinum (Pt)-based catalysts are widely used in fuel cells and hydrogen energy generation (for example, via water electrolysis). However, reducing the amount of Pt used while maintaining the catalytic performance of such catalysts is essential. Herein, PtLa catalysts (Pt x La y /C) doped with rare earth element lanthanum (La) with different Pt/La atomic ratios were synthesized using a simple chemical reduction method, resulting in Pt 65 La 35 /C, Pt 78 La 22 /C, Pt 97 La 3 /C, and Pt 100 /C. These Pt x La y /C catalysts exhibited excellent electrocatalytic activity and stability in methanol oxidation reaction (MOR), hydrogen evolution reaction (HER), and their coupling reaction as MOR||HER under alkaline conditions. The mechanism by which La doping enhances the electrocatalytic properties and stability of Pt-based catalysts was investigated using X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), aberration-corrected scanning transmission electron microscopy (AC-STEM), in-situ Fourier transform infrared (FTIR) and operando Raman spectroscopy. For HER, La doping facilitated the adsorption and activation of H 2 O at Pt sites, improving water dissociation and *OH desorption and reducing Pt poisoning by *OH. This enhances both the catalytic performance and stability of Pt x La y /C for HER. Pt 78 La 22 /C exhibited a considerably lower overpotential of only 111 mV at 100 mA cm−2 compared to commercial 20 wt% Pt/C (Pt/C-Johnson Matthey (JM)), which requires 153 mV. For MOR, La promotes C O bond cleavage and reduces CO adsorption at the Pt sites, thereby enhancing both the performance and stability of the catalysts. The mass activity (MA) of Pt 78 La 22 /C for MOR is 4.44 A mg−1 Pt , which is 12.33 times higher than that of Pt/C-JM (0.36 A/mg Pt), and surpasses those of Pt 65 La 35 /C, Pt 97 La 3 /C, and Pt 100 /C (2.93, 0.24, and 2.91 A mg−1 Pt , respectively). Additionally, Pt 78 La 22 /C exhibited outstanding catalytic performance for MOR||HER, with a current density of 20 mA cm−2 at 1.030 V, demonstrating good stability with negligible voltage changes after a 15 h chronoamperometry (CA) testing. This study provides a new strategy for synthesizing Pt-based catalysts with enhanced efficiency and low-energy input for HER||MOR. [ABSTRACT FROM AUTHOR]

[Display omitted] • The SGTA and SGT colloidal solutions are synthesized by the sol–gel method. • The surface of SGTA is stabilized from severe aggregation compared to SGT particles. • The SGTA@CF has the highest charge transfer kinetics for the V3+ → V2+ reaction. • This is due to the dense even coating on fibers that inhibits the competitive HER. • The SGT@CF experiences parasitic HER and high R CT , as in P-CF. The occurrence of the hydrogen evolution reaction (HER) on the surface of the carbon-based negative electrode of the vanadium redox flow battery (VRFB) causes high charge transfer resistance (R CT) for the desired V3+/V2+ redox reaction leading to irreversible capacity loss. To this effect, we have synthesized acetylacetonate-modified TiO 2 (SGTA) and unmodified TiO 2 (SGT) coating colloidal solutions as electrocatalysts for enhanced V3+/V2+ redox reaction on the carbon-felt negative electrodes of VRFB. The SGTA particles exhibit significantly higher homogeneity with sizes of ≤15 nm, in comparison to the severely aggregated SGT particles with diameters of ∼23–75 nm in colloidal solution. When coated on the pristine carbon felt (P-CF), the surface morphology of the SGTA@CF electrode exhibits relatively dense, uniformly coated particles, in comparison to the sparse, non-even coating of aggregated particles on the SGT@CF electrode surface. Consequently, the charge transfer for V3+ → V2+ reduction reaction and charge storage capacity are determined to be in the order SGTA@CF > SGT@CF > P-CF, confirming that the competitive and irreversible HER was higher on the surface of non-evenly coated fibers and bare carbon felt, respectively. [ABSTRACT FROM AUTHOR]

[Display omitted] • Using MOF as a precursor to obtain mesopore-rich titanium dioxide and achieve uniform copper dispersion. • The porous structure is beneficial to expose copper nanoparticle to improve atom utilization. • Use Cu as both dopant and co-catalyst to enhance hydrogen production activity. Metal-doping is a common strategy for establishing active sites on photocatalyst, but appropriately exposing them for maximized atomic utilization remains a great challenge in photocatalytic research. Herein, we propose a metal organic framework (MOF)-assisted approach to synthesis copper-modified titania (Cu-TiO 2 /Cu) photocatalyst with homogenously distributed and highly accessible active sites in its matrix. Significantly, an MOF precursor, namely NH 2 -MIL-125, with co-chelation of titania (Ti) and copper (Cu) was subjected to mild calcination, subsequently results in Cu-modified TiO 2 with highly accessible channels to its inner surface. These channels provide not only a large reactive surface (>400 m2 g-1); they also enable facile modifying route for the pre-deposited Cu in prior to photoreaction. Specifically, NH 3 treatment was applied to partially reduce deposited Cu ions (Cu+ and Cu2+) into Cu nanoparticles, where their interplays realize improved optical properties and charge separation during photoreactions. Furthermore, the NH 3 -induced Cu nanoparticles could also serve as the adsorptive site for H+, thereby enabling 5629 μmol h-1 g-1 H 2 generation over the optimum photocatalyst of Cu 20 /TiO 2 /Cu 500. Such performance is associated to 35.44 and 1.71-fold improvements compared to pure TiO 2 (Cu 0 /TiO 2) and untreated Cu-ion modified TiO 2 (Cu 20 /TiO 2), respectively. This work offers a new synthetic strategy for obtaining photocatalyst with evenly distributed and highly accessible active sites, thus improving the commensurability of photocatalytic H 2 generation from the industrial perspective. [ABSTRACT FROM AUTHOR]

[Display omitted] The single atom catalysts (SACs) show immense promise as catalytic materials. By doping the single atoms (SAs) of precious metals onto substrates, the atomic utilization of these metals can be maximized, thereby reducing catalyst costs. The electronic structure of precious metal SAs is significantly influenced by compositions of doped substrates. Therefore, optimizing the electronic structure through appropriate doping of substrates can further enhance catalytic activity. Here, Pt single atoms (Pt SAs) are doped onto transition metal sulfide substrate NiS 2 (Pt SAs-NiS 2) and phosphide substrate Ni 2 P (Pt SAs-Ni 2 P) to design and prepare catalysts. Compared to the Pt SAs-NiS 2 catalyst, the Pt SAs-Ni 2 P catalyst exhibits better hydrogen evolution catalytic performance and stability. Under 1 M KOH conditions, the hydrogen evolution mass activity current density of the Pt SAs-Ni 2 P catalyst reaches 0.225 A mg Pt –1 at 50 mV, which is 33 times higher than that of commercial Pt/C catalysts. It requires only 44.9 mV to achieve a current density of 10 mA cm−2. In contrast, for the Pt SAs-NiS 2 catalyst, the hydrogen evolution mass activity current density is 0.178 A mg Pt –1, requiring 77.8 mV to achieve a current density of 10 mA cm−2. Theoretical calculations indicate that in Pt SAs-Ni 2 P, the interaction between Pt SAs and the Ni 2 P substrate causes the Pt d-band center to shift downward, enhancing the H 2 O desorption and providing optimal H binding sites. Additionally, the hollow octahedral morphology of Ni 2 P provides a larger surface area, exposing more reactive sites and improving reaction kinetics. This study presents an effective pathway for preparing high-performance hydrogen evolution electrocatalysts by selecting appropriate doped substrates to control the electronic structure of Pt SAs. [ABSTRACT FROM AUTHOR]

[Display omitted] Developing high active and stable cost-effective bifunctional electrocatalysts for overall water splitting to produce hydrogen is of vital significance in clean and sustainable energy development. This work has prepared a novel porous unreported MOF (Ni-DPT) as a precursor to successfully synthesize a non-noble bifunctional NiCoP/Ni 12 P 5 @NF electrocatalyst through doping strategy and interface engineering. This catalyst is constructed by layered self-supporting arrays with heterojunction interface and rich nitrogen-phosphorus doping. Structural characterizations and the density function theory (DFT) calculations confirm that the interface effect of NiCoP/Ni 12 P 5 heterojunction can regulate the electronic structure of the catalyst to optimize the Gibbs free energy of hydrogen (ΔG H*); simultaneously, the defect-rich layered nanoarrays can expose more active sites, shorten mass transfer distance, and generate a self-supporting structure for in-situ reinforcing the structural stability. As a result, this NiCoP/Ni 12 P 5 @NF catalyst exhibits favorable electrocatalytic performance, which simply needs overpotentials of 100 mV for HER and 310 mV for OER, respectively, at a current density of 10 mA·cm−2. The anion exchange membrane electrolyzer assembled with this NiCoP/Ni 12 P 5 @NF as both anode and cathode catalysts can operate stably for 200 h at a current density of 100 mA·cm−2 with an insignificant voltage decrease. This work may provide some inspiration for the further rational design of inexpensive non-noble multifunctional electrocatalysts and electrode materials for water splitting to generate hydrogen. [ABSTRACT FROM AUTHOR]

Abstract In this study, we investigate the catalytic performance of molybdenum sulfide (MoS2) modified with either nickel (Ni) or platinum (Pt) nanoparticles as catalysts for the hydrogen evolution reaction (HER). The MoS2 was prepared on the TiO2 nanotube substrates via a facile hydrothermal method, followed by the deposition by magnetron sputtering of Ni or Pt nanoparticles on the MoS2 surface. Structural and morphological characterization confirmed the successful incorporation of Ni or Pt nanoparticles onto the MoS2 support. Electrochemical measurements revealed that Ni- and Pt-modified MoS2 catalysts exhibited enhanced HER activity compared to pristine MoS2. Obtained catalysts demonstrated a low onset potential, reduced overpotential, and increased current density, indicating efficient electrocatalytic performance. Furthermore, the Ni or Pt-modified MoS2 catalyst exhibited remarkable stability during prolonged HER operation. The improved catalytic activity can be attributed to the synergistic effect between metal nanoparticles and MoS2, facilitating charge transfer kinetics and promoting hydrogen adsorption and desorption. Incorporating Ni and Pt nanoparticles also provided additional active sites on the MoS2 surface, enhancing the catalytic activity.

The development of hydrogen storage and conversion technologies, such as electrolyzers and fuel cells, significantly benefits from the electrochemical deposition of platinum (Pt). This process is also crucial for creating coatings for internal combustion engines and electronic devices. Conventionally, Pt electrochemical deposition occurs in acidic media, which efficiently dissolves Pt salts but necessitates the use of expensive, corrosion-resistant substrates like noble metals and other critical raw materials such as titanium (Ti). This research explores the alkaline electrochemical deposition of Pt, aiming to overcome the limitations associated with acidic media. The study begins with developing strategies to dissolve commonly used Pt precursors from acidic baths into stable complexes suitable for alkaline environments. Various protocols, including chronoamperometric and potentiometric ones, are employed to evaluate the Pt electrodeposition on substrates such as nickel (Ni) foams and stainless steel meshes, which are relevant to alkaline water electrolysis. Optimization of the electrochemical deposition parameters is carried out to enhance the hydrogen evolution reaction (HER) activity of the resulting electrodes. The most HER-active electrodes are then tested as cathodes in alkaline electrolyzers (AELs), demonstrating superior performance compared to commercially available platinized Ti felts. These advanced AELs can operate at high current densities (≥1 A cm⁻2) at cell voltages below 2 V, thereby rivaling state-of-the-art acidic water electrolysis systems. Looking forward, the alkaline electrodeposition of Pt presents a sustainable approach to the usage of Pt in green hydrogen production. Pt recovered from operating or end-of-life electrolyzers and fuel cells can be reused to restore or enhance the catalytic activity of cathodes in alkaline water electrolysis, ensuring efficient and eco-friendly Pt utilization. [Display omitted] • Alkaline electrochemical deposition of Pt explored on various substrates used in AELs and AEM-ELs. • Pt precursors can form stable complexes in 1 M and 6.9 M KOH at 70 °C. • Fine-tuned Pt films achieve overpotential as low as 0.067 V at −100 mA cm⁻2. • Electrochemically deposited Pt films were validated in high-performance AEL cells. • In-situ electrochemical Pt deposition can be used for upgrading/healing AEL and AEM-EL cathodes. [ABSTRACT FROM AUTHOR]

Boron subphthalocyanines with chloride and fluoride axial ligands and three antimony complexes chelated by corroles that differ in size and electron‐richness were examined as electrocatalysts for reduction of protons to hydrogen. Experiment‐ and computation‐based investigations revealed that all redox events are ligand‐centered and that the meso‐C of the corroles and the peripheral N atoms of the subphthalocyanines are the largely preferred proton‐binding sites. [ABSTRACT FROM AUTHOR]

The advancement of a sustainable and scalable catalyst for hydrogen production is crucial for the future of the hydrogen economy. Electrochemical water splitting stands out as a promising pathway for sustainable hydrogen production. However, the development of Pt‐free electrocatalysts that match the energy efficiency of Pt while remaining economical poses a significant challenge. This review addresses this challenge by highlighting latest breakthroughs in Pt‐free catalysts for the hydrogen evolution reaction (HER). Specifically, we delve into the catalytic performance of various transition metal phosphides, metal carbides, metal sulphides, and metal nitrides toward HER. Our discussion emphasizes strategies for enhancing catalytic performance and explores the relationship between structural composition and the performance of different electrocatalysts. Through this comprehensive review, we aim to provide insights into the ongoing efforts to overcome barriers to scalable hydrogen production and pave the way for a sustainable hydrogen economy. [ABSTRACT FROM AUTHOR]

Modern civilization has been highly suffering from energy crisis and environmental pollutions. These two burning issues are directly and indirectly created from fossil fuel consumption and uncontrolled industrialization. The above critical issue can be solved through the proper utilization of green energy sources where no greenhouse gases will be generated upon burning of such materials. Hydrogen is the most eligible candidate for this purpose. Among various methods of hydrogen generation, electrocatalytic process is one of the most efficient methods because of easy handling and high efficiency. In these aspects Co‐based nanomaterials are considered to be extremely significant as they can be utilized as efficient, recyclable and ideal catalytic system. In this article a series of Co‐based nano‐electrocatalysts has been discussed with proper structure‐property relationship and their medium dependency. Therefore, such type of stimulating summary on recently reported electrocatalysts and their activity may be helpful for scientists of the corresponding field as well as for broader research communities. This can be inspiration for materials researchers to fabricate active catalysts for the production of hydrogen gas in room temperature. [ABSTRACT FROM AUTHOR]

The quest for sustainable and clean energy sources has intensified research on the Hydrogen Evolution Reaction (HER) in recent decades. In this study, we have presented a novel Ce‐doped TiO2 catalyst synthesized through the sol‐gel method, showcasing its potential as a superior electrocatalyst for HER in an acidic medium. Comprehensive characterization through X‐ray diffraction (XRD), X‐ray photoelectron spectroscopy (XPS), Energy dispersive X‐ray (EDX), and Raman spectroscopy confirms the successful formation of the catalyst. Electrocatalytic performance evaluation, including open circuit potential (OCP), electrochemical impedance spectroscopy (EIS), and Tafel analysis, demonstrates that GCE‐5wt.%CeTiO2 outperforms bare GCE, as well as Ce and TiO2‐based electrodes. Kinetic investigations reveal a Tafel slope of 105 mV dec−1, indicating the Volmer step as the rate‐determining step. The onset potential for HER at GCE‐5wt.%CeTiO2 is −0.16 V vs. RHE, close to the platinum electrode. Notably, the catalyst exhibits a low overpotential of 401 mV to achieve a current density of 10 mA cm−2 with an impressive 95 % Faradaic efficiency. Furthermore, the catalyst demonstrates outstanding durability, maintaining a negligible increase in overpotential during a 14‐hour chronoamperometry test. These results have far‐reaching implications for the development of cost‐effective and efficient electrocatalysts for hydrogen production. [ABSTRACT FROM AUTHOR]

In this paper, we report an inexpensive one-step synthesis of self-supported 3D nickel-manganese (NiMn) bimetallic coatings and their application for the hydrogen evolution reaction in simulated seawater (1 M KOH + 0.5 M NaCl) and alkaline natural seawater (1 M KOH + natural seawater). These binary coatings were electrodeposited on a titanium substrate using a facile electrochemical deposition method by a dynamic hydrogen bubble template technique. The as-deposited NiMn coatings with variable Mn amounts produce typical globular and unique porous architecture with abundant pores of different sizes. The activity of these fabricated catalysts towards the hydrogen evolution reaction was investigated by linear sweep voltammetry towards simulated seawater and alkaline natural seawater at different temperatures. The surface morphology and composition of the catalysts were also characterized by scanning electron microscopy and inductively coupled plasma optical emission spectroscopy. The as-prepared NiMn/Ti electrocatalyst, which was electrodeposited using a chemical bath containing Ni2+ and Mn2+ ions with a molar ratio of Ni2+:Mn2+ = 1:5, exhibits excellent hydrogen evolution activity in simulated seawater with an ultra-low overpotential of 64.2 mV to reach a current density of 10 mA cm−2. It is noteworthy that this NiMn/Ti electrocatalyst also achieves a current density of 10 mA cm−2 in alkaline natural seawater with a comparably low overpotential of 79.3 mV. The current densities increase by ca. 1.75–2.35 times with an increase in temperature from 25 °C to 75 °C for hydrogen evolution in both electrolytes. This bimetallic catalyst has shown excellent long-term stability at a constant potential of −0.23 V (vs. RHE) and a constant current density of 10 mA cm−2 for 10 h, which ensures higher durability and robustness for practical application of seawater splitting technology. [Display omitted] • 3D bimetallic NiMn/Ti electrocatalysts synthesized using a dynamic hydrogen bubble template technique. • Efficient and stable 3D bimetallic NiMn/Ti electrocatalysts for HER in simulated seawater/alkaline natural seawater. • NiMn/Ti-5 shows excellent HER activity with overpotentials of 64.2 and 79.3 mV at 10 mAcm−2 in simulated and natural seawater. • Simple, non-toxic, affordable, and time-saving synthesis procedure. [ABSTRACT FROM AUTHOR]

Precise design and synthesis of sub-nano scale catalysts with controllable electronic and geometric structures are pivotal for enhancing the hydrogen evolution reaction (HER) performance of molybdenum sulfide (MoS2) and unraveling its structure-activity relationship. By leveraging transition molybdenum polysulfide clusters as functional units for multi-level ordering, we successfully designed and synthesized MoSx nanowire networks derived from [Mo3S13]2− clusters via evaporation-induced self-assembly, which exhibit enhanced HER activity attributed to a high density of active sites and dynamic evolution behavior under cathodic potentials. MoSx nanowire networks electrode yields a current density of 100 mA·cm−2 at 142 mV in 0.5 M H2SO4. This work provides an attractive prospect for optimizing catalysts at the sub-nano scale and offers insights into a strategy for designing catalysts in various gas evolution reactions. [ABSTRACT FROM AUTHOR]

In the present work, the highly effective nanoscale Cu-modified dark TiO2 photocatalysts for hydrogen evolution reactions are prepared by pulsed laser ablation with and without additional laser treatment (ALT). Transmission electron microscopy HR results show that copper is distributed along the dark titania surface both in the form of subnanometer oxide clusters and single atoms (SAs). After the ALT, the Cu dispersion increases, and a large number of SAs appear. The X-ray photoelectron spectroscopy data indicate that the increasing copper content as well as the ALT lead to an increase in the surface Ti3+ content. Copper on the surface exists in the Cu+ state, which is associated with the strong metal-support interaction (SMSI) effect between the defective TiO2 support and a SA/subnanometer cluster of copper. Photocatalytic activity of nanoscale Cu-modified dark TiO2 is studied in the hydrogen evolution from aqueous glycerol solution under irradiation with light-emitting diodes (LEDs) 375 (soft ultraviolet) and LED 410 (visible region). In all cases, the modification of the surface with copper significantly increases the hydrogen yield in both the UV and visible regions. The ALT also leads to an increase in the photocatalytic activity of materials due to an increase in the SMSI between copper species and the surface of the dark TiO2. For the process of photocatalytic hydrogen evolution, a mechanism is proposed, and the products of glycerol photooxidation are identified. [ABSTRACT FROM AUTHOR]

Modifying the electronic structure of a catalyst through interface engineering is an effective strategy to enhance its activity in the hydrogen evolution reaction (HER). Interface engineering is a viable strategy to enhance the catalytic activity of transition metal phosphides (TMPs) in the HER process. The interface-engineered FeP/NiP2/Ni5P4/NiP multi-metallic phosphide nanoparticles confined in a N, P-doped carbon matrix was developed by a simple one-step low-temperature phosphorization treatment, which only requires 72 and 155 mV to receive the current density of 10 mA/cm2 in acid and alkaline electrolyte, respectively. This enhanced performance can be primarily attributed to the heterointerface of FeP/NiP2/Ni5P4/NiP multi-metallic phosphides, which promotes electron redistribution and optimizes the adsorption/desorption strength of H* on the active sites. Furthermore, the N, P-doped carbon framework that encapsulates the nanoparticles inhibits their aggregation, leading to an increased availability of active sites throughout the reaction. The results of this study open up a straightforward and innovative approach to developing high-performance catalysts for hydrogen production. [ABSTRACT FROM AUTHOR]

By a two-step method, we successfully synthesized a WS 2 /WO 3-x heterostructured catalysts with abundant oxygen vacancies. The WS 2 /WO 3-x -2 heterostructured catalyst demonstrates outstanding HER activity and stability in acidic and alkaline electrolytes. [Display omitted] H 2 produced through hydrogen evolution reaction (HER) is a shining star in the field of clean energy. Significant efforts have been dedicated to develop efficient and stable electrocatalysts to reduce the energy barrier and accelerate the kinetics of Hydrogen evolution reaction (HER) under various environments. Herein, we propose a strategy to accelerate the kinetics of HER under acid and alkaline environments by combining heterostructure engineering with defect engineering. We have successfully synthesized a series of WS 2 /WO 3-x heterostructured catalysts, accompanied with substantial oxygen vacancies using a two-step synthesis method. With the partially sulfurization of WO 3-x , the heterojunction interface of WS 2 and WO 3-x was formed along with the appearance of oxygen vacancies, which can facilitate the migration of electrons. The heterostructured catalyst enriched with oxygen vacancies (defined as WS 2 /WO 3-x -2) demonstrates superior HER performance in acidic and alkaline electrolytes. At a current density of 10 mA cm−2, the WS 2 /WO 3-x -2 heterostructured catalyst manifests an overpotential of 120 mV in the acidic electrolytes and a slightly higher overpotential of 150 mV in an alkaline environment. The overpotentials offer an improvement compared to reported W-based catalysts in terms of HER performance. This work provides guiding significance on the design of heterostructured catalysts with promising performance for HER in acidic and alkaline environments. [ABSTRACT FROM AUTHOR]

Developing highly active and durable platinum-based catalysts is crucial for electrochemical renewable energy conversion technologies but the limited supply and high cost of platinum have hindered their widespread implementation. The incorporation of non-noble metals, particularly copper, into Pt catalysts has been demonstrated as an effective solution to reduce Pt consumption while further promoting their performance, making them promising for various electrocatalytic reactions. This review summarizes the latest advances in PtCu-based alloy catalysts over the past several years from both synthetic and applied perspectives. In the synthesis section, the selection of support and reagents, synthesis routes, as well as post-treatment methods at high temperatures are reviewed. The application section focuses not only on newly proposed electrochemical reactions such as nitrogen-related reactions and O2 reduction but also extends to device-level applications. The discussion in this review aims to provide further insights and guidance for the development of PtCu electrocatalysts for practical applications. [ABSTRACT FROM AUTHOR]

The exfoliation of bulk 2H-molybdenum disulfide (2H-MoS2) into few-layer nanosheets with 1T-phase and controlled layers represents a daunting challenge towards the device applications of MoS2. Conventional ion intercalation assisted exfoliation needs the use of hazardous n-butyllithium and/or elaborate control of the intercalation potential to avoid the decomposition of the MoS2. This work reports a facile strategy by intercalating Li ions electrochemically with ether-based electrolyte into the van der Waals (vdW) channels of MoS2, which successfully avoids the decomposition of MoS2 at low potentials. The co-intercalation of Li+ and the ether solvent into MoS2 makes a first-order phase transformation, forming a superlattice phase, which preserves the layered structure and hence enables the exfoliation of bulk 2H-MoS2 into bilayer nanosheets with 1T-phase. Compared with the pristine 2H-MoS2, the bilayer 1T-MoS2 nanosheets exhibit better electrocatalytic performance for the hydrogen evolution reaction (HER). This facile method should be easily extended to the exfoliation of various transition metal dichalcogenides (TMDs). [ABSTRACT FROM AUTHOR]

The growing interest in hybrid (aqueous–organic) electrolytes for electrochemical energy storage is due to their wide stability window, improved safety, and ease of assembly that does not require a moisture-free atmosphere. When it comes to applications in electrochemical capacitors, hybrid electrolytes are expected to fill the gap between high-voltage organic systems and their high discharge rate aqueous counterparts. This article discusses the potential applicability of aqueous–organic electrolytes utilizing water/N,N-dimethylacetamide (DMAc) solvent mixture, and sodium perchlorate as a source of charge carriers. The hydrogen bond formation between H2O and DMAc (mole fraction xDMAc = 0.16) is shown to regulate the original water and cation solvation structure, thus reducing the electrochemical activity of the primary aqueous solution both in the hydrogen (HER) and oxygen (OER) evolution reactions region. As a result, an electrochemical stability window of 3.0 V can be achieved on titanium electrodes while providing reasonable ionic conductivity of 39 mS cm−1 along with the electrolyte's flame retardant and anti-freezing properties. Based on the diagnostic electrochemical studies, the operation conditions for carbon/carbon capacitors have been carefully optimized to adjust the potential ranges of the individual electrodes to the electrochemical stability region. The system with the appropriate electrode mass ratio (m+/m− = 1.51) was characterized by a wide operating voltage of 2.0 V, gravimetric energy of 13.2 Wh kg−1, and practically a 100% capacitance retention after 10,000 charge–discharge cycles. This translates to a significant rise in the maximum energy of 76% when compared to the aqueous counterpart. Additionally, reasonable charge–discharge rates and anti-freeze properties of the developed electrolyte enable application in a broad temperature range down to −20 °C, which is demonstrated as well. [ABSTRACT FROM AUTHOR]

The use of two-dimensional (2D) layered metal-organic frameworks (MOFs) as self-sacrificial templates has been proven to be a successful method to create high-efficiency Selenium (Se)-containing electrocatalysts for overall water splitting. Herein, two strategies are then utilized to introduce Se element into the Co–Fe MOF, one being the etching of as-prepared MOF by SeO2 solution, and the other, the replacing of SCN− with SeCN− as the construction unit. The electrochemical activity of the pristine 2D MOF and their calcinated derivatives for catalyzing the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) is evaluated and further discussed. It is found that the effect of introducing Se on improving electrochemical catalytic activity is significant for the HER process. Specifically, the calcinated derivative in the replacing method exhibits an overpotential of 235 mV for HER and 270 mV for OER at a current density of 10 mA/cm2. For comparing the two methods of introducing Se element into MOF, similar electrocatalytic activity can be achieved on the their calcinated derivatives. The high electrochemical performance of 2D CoFe-MOF derivatives may be resulted from the unique 2D hierarchical porous structure and strong synergistic effect between different components in the material. [ABSTRACT FROM AUTHOR]

Using the electrochemical technology to split water molecules to produce hydrogen is the key to obtain green hydrogen for solving the energy crisis. The large-scale application of hydrogen evolution reaction (HER) in water dissociation requires a highly active catalyst. In this paper, the highly dispersed PtCo bimetallic nanoparticles loading on MXene (PtCo/MXene) were prepared by using a step-to-step reduction strategy. The mentioned PtCo/MXene catalyst exhibits a high current density of −100 mA/cm2 in an acidic medium with just a 152 mV overpotential. In addition, the PtCo/MXene catalyst also displays a superior stability. Computational analysis and experimental testing demonstrate that the electronic interaction between Pt and Co can effectively modify the electronic structure of the active site, thereby enhancing the inherent catalytic performance of the material. More importantly, MXene two-dimensional nanosheets can expose more active sites because of their large specific surface area. Furthermore, MXene substrate with excellent electrical conductivity and harmonious interfaces between PtCo and MXene enhance charge transfer efficiency and lower the reaction activation energy. [ABSTRACT FROM AUTHOR]

The development of renewable and affordable energy is crucial for building a sustainable society. In this context, establishing a sustainable infrastructure for renewable energy requires the integration of energy storage, specifically use of renewable hydrogen. The hydrogen evolution reaction (HER) of electrochemical water splitting is a promising method for producing green hydrogen. Recently, two-dimensional nanomaterials have shown great promise in promoting the HER in terms of both fundamental research and practical applications due to their high specific surface areas and tunable electronic properties. Among them, molybdenum disulfide (MoS2), a non-noble metal catalyst, has emerged as a promising alternative to replace expensive platinum-based catalysts for the HER because MoS2 has a high inherent activity, low cost, and abundant reserves. At present, greatly improved activity and stability are urgently needed for MoS2 to enable wide deployment of water electrolysis devices. In this regard, efficient strategies for precisely modifying MoS2 are of interest. Herein, the progress made with MoS2 as an HER catalyst is reviewed, with a focus on modification strategies, including phase engineering, morphology design, defect engineering, heteroatom doping, and heterostructure construction. It is believed that these strategies will be helpful in designing and developing high-performance and low-cost MoS2-based catalysts by lowering the charge transfer barrier, increasing the active site density, and optimizing the surface hydrophilicity. In addition, the challenges of MoS2 electrocatalysts and perspectives for future research and development of these catalysts are discussed. [ABSTRACT FROM AUTHOR]

The transition towards hydrogen energy is paramount due to its potential to mitigate environmental pollution caused by fossil fuels. The greener and cleaner way of producing and utilizing hydrogen is through water electrolysis and hydrogen fuel cell where the sluggish reaction kinetics bottlenecks the widescale implementation. Hence, in this study, density functional theory (DFT) is utilized to study the HER, OER and ORR performance of pristine and doped silicene sheets where the dopants (B, C, N, Al and P) are introduced as single atom. The thermodynamical stability for pristine and doped sheets are confirmed with ADMP study and the cohesive energy for all the sheets are found to be around -4.2 eV per atom which validates their stability. The hydrogen evolution reaction (HER) performance of all the sheets is studied and the N doped silicene exhibits better catalytic property with a lowest overpotential of 70 mV and the C doped silicene shown good HER performance with an overpotential of 180 mV. In case of oxygen evolution reaction (OER) and oxygen reduction reaction (ORR), the pristine silicene is found to behave better in the ORR performance while the C doped silicene has the lowest overpotential compared with the other sheets. The variation in the catalytic performance is studied with the reactivity parameters which implies that the nucleophilic nature of the material enhances the HER performance. Furthermore, the results suggest that C doped silicene can be utilized as a bifunctional catalyst for the HER and OER performance. This study suggests that the silicene in the pure form as well as with dopant can be a good electrocatalyst for the water splitting and fuel cell application.

The present study emphasizes the enhancement in catalytic activity due to the formation of vacancies using dispersion corrected density functional theory. We observed that without vacancy formation, in general the edge site is an active site for hydrogen adsorption, while the lowest Gibbs free energy (ΔGH) is found to be for Janus HfSSe at the S-edge site. Furthermore, interestingly, due to the hindrance of the edge site, it facilitates only the Volmer-Heyrovsky reaction rather than the Volmer-Tafel. Among the mono vacancies, the Hafnium mono vacancy shows the lowest adsorption energy. We observed a competition between the evolution of H 2 S and H 2 gas in the case of HfS 2 -V Hf , whereas in the case of defected Janus and HfSe 2 , due to the presence of Se layers, we observed no competitiveness with H 2 S or H 2 Se gas with hydrogen gas. These defected materials exhibit lower reactional Gibbs free energy than a pristine monolayer due to its metallic nature. We observed that Hafnium vacancy enhances the HER activity, and pave the way for dominating Volmer-Heyrovsky reaction. [Display omitted] • HfS 2 and Janus HfSSe are potential candidates for photo-catalyst. HfSe 2 exhibits its potential use as an electrocatalyst. • The order of hydrogen adsorption efficiency is HfSSe > HfS 2 > HfSe 2. • Defect engineering is employed to enhance the catalytic efficiency of pristine compounds. • After defect creation, HfS 2 is most favourable for HER followed by HfSe 2 and HfSSe. [ABSTRACT FROM AUTHOR]

This study reported a multi–functional Co0.45Fe0.45Ni0.9–MOF/NF catalyst for oxygen evolution reaction (OER), hydrogen evolution reaction (HER), and overall water splitting, which was synthesized via a novel shape–preserving two–step hydrothermal method. The resulting bowknot flake structure on NF enhanced the exposure of active sites, fostering a superior electrocatalytic surface, and the synergistic effect between Co, Fe, and Ni enhanced the catalytic activity of the active site. In an alkaline environment, the catalyst exhibited impressive overpotentials of 244 mV and 287 mV at current densities of 50 mA cm−2 and 100 mA cm−2, respectively. Transitioning to a neutral environment, an overpotential of 505 mV at a current density of 10 mA cm−2 was achieved with the same catalyst, showing a superior property compared to similar catalysts. Furthermore, it was demonstrated that Co0.45Fe0.45Ni0.9–MOF/NF shows versatility as a bifunctional catalyst, excelling in both OER and HER, as well as overall water splitting. The innovative shape–preserving synthesis method presented in this study offers a facile method to develop an efficient electrocatalyst for OER under both alkaline and neutral conditions, which makes it a promising catalyst for hydrogen production by water splitting. [ABSTRACT FROM AUTHOR]

The development of an efficient and stable electrocatalyst for the hydrogen evolution reaction (HER), based on earth‐abundant components, represents a crucial step toward cost‐effective and environmentally friendly hydrogen production. This study presents the utilization of a dinuclear copper catalyst, denoted as [Cu‐Gly‐SB] (Complex 1), for HER under both aqueous and non‐aqueous conditions. In non‐aqueous settings, the catalyst achieves excellent HER performance, requiring only a 270 mV overpotential when acetic acid is used as the proton donor. Notably, in fully aqueous conditions, complex 1 attains a remarkable current density of 18.8 mA ⋅ cm−2 at −0.7 V vs. RHE in cyclic voltammetry. The kobs value of ≈2.7×104 s−1 in aqueous solution at pH 7.0 further underlines the superior catalytic performance of 1, outperforming most non‐noble‐metal molecular catalysts functioning in fully aqueous solutions. The robust stability of 1 is demonstrated through controlled potential electrolysis (CPE) over a span of 48 hours, achieving an impressive catalytic current of 11.0 mA ⋅ cm−2 at −0.39 V. Moreover, the catalytic current gradually increases with higher reduction potentials, reaching a substantial 100 mA ⋅ cm−2 at an overpotential of 590 mV during CPE >48 hours. Thorough characterizations further confirm the molecular nature of the catalyst. [ABSTRACT FROM AUTHOR]

The paper presents an original method for synthesizing high-density composite ceramics with a Mo 2 C/Mo 3 Co 3 C composition using the technology of high-speed Spark Plasma Sintering (SPS) of a mechanically activated powder mixture of Mo 2 C-10 wt%Co. The activated homogeneous starting mixture was obtained by wet milling/activation of the initial powders of Mo 2 C and Co in an anhydrous isopropanol medium. The ceramic samples were consolidated by SPS under vacuum (10−5 atm.) at 1000, 1100, 1150, and 1200 °C with a heating rate of 87.3 °C·min−1 under constant external uniaxial pressing pressure of 50 MPa. The sintering kinetics were studied, the twofold nature of sintering was established, and the temperature range of active densification was determined. The ceramic synthesis is accompanied by a reactive interaction of the components, resulting in the formation of the Mo 3 Co 3 C phase and a change in the crystal lattice of the non-stoichiometric Mo 2 C x compound. The ceramic obtained in the temperature interval of the isothermal sintering stage of 1150–1200 °C is homogeneous in the distribution of Mo and Co, consists of a Mo 2 C/Mo 3 Co 3 C phase mixture, has a density value of 98.13 ± 0.5 % theoretical density, and has an average Vickers hardness value of ∼1526 HV. Increasing the sintering temperature to 1200 °C results in the formation of almost monolithic structures in the samples, but also induces the formation of large defects due to the collective consolidation of pores within the bulk material and increases the susceptibility of the ceramic to cracking. The paper presents preliminary results from electrochemical testing. The proposed method for synthesizing Mo 2 C/Mo 3 Co 3 C ceramics has potential for use in optimizing the composition and production methods of electrode materials for the realization of active components in heterostructured electrodes used for hydrogen evolution. [ABSTRACT FROM AUTHOR]

Designing a long-lasting, highly effective, non-noble metal-free electrocatalyst for both hydrogen evolution reaction (HER) and the oxygen evolution reaction (OER) is a strenuous task for water electrolysis. Here, in our study, an ordered NiFe-layer double hydroxide (LDH)/MoSe 2 as p-n junction material was designed using facile two-step hydrothermal process for the overall water splitting reaction. Additionally, synthesized NiFe-LDH/MoSe 2 , electrode exhibits long-term durability in both acidic and alkaline medium for HER and OER, respectively. Mott-Schottky experiments provides the insights of interfacial electron transfer, where the electron is transported from n-type NiFe-LDH to p-type MoSe 2 , resulting in the generation of the p-n junction in MoSe 2 /NiFe-LDH. As the formation LDH and transition dichalcogenides p-n junction leads to activation of the catalysts towards the OH− adsorption that may enable the water electrolysis with a low overpotential. The XPS analysis supports the electron transfer from Fe to Mo resulting in the formation synergistic back bonding between the p-n heterojunction. This strategy opens up an alternative path to a highly effective, relatively low-price catalyst for the global production of renewable energy fuels. • A highly ordered NiFe-layer double hydroxide (LDH)/MoSe 2 as p-n junction catalyst for overall water splitting reaction. • Interfacial electron transfer, through the generation of the p-n junction in NiFe-LDH/MoSe 2. • Electronic coupling through O 2 bridging (П orbitals) confirmed from XPS analysis. [ABSTRACT FROM AUTHOR]

Doping foreign metal atoms into the substrate of transition metal dichalcogenides (TMDs) enables the formation of diverse atomic structure configurations, including isolated atoms, chains, and clusters. Therefore, it is very important to reasonably control the atomic structure and determine the structure–activity relationship between the atomic configurations and the hydrogen evolution reaction (HER) performance. Although numerous studies have indicated that doping can yield diverse atomic structure configurations, there remains an incomplete understanding of the relationship between atomic configurations within the lattice of TMDs and their performance. Here, diverse atomic structure configurations of adsorptive doping, substitutional doping, and TMDs alloys are summarized. The structure–activity relationship between different atomic configurations and HER performance can be determined by micro-nanostructure devices and density functional theory (DFT) calculations. These diverse atomic structure configurations are of great significance for activating the inert basal plane of TMDs and improving the catalytic activity of HER. Finally, we have summarized the current challenges and future opportunities, offering new perspectives for the design of highly active and stable metal-doped TMDs catalysts. [ABSTRACT FROM AUTHOR]

Catalytically driven electrochemical hydrogen evolution reaction (HER) holds immense promise for meeting renewable energy demands. In this study, we have reported highly efficient HER catalyst utilizing a novel electrode composed of titanium (Ti) sheet with gold and iridium oxide (Ti/Au-IrO x), compared to a conventional Pt electrode. The fabrication process involved anodizing a Ti strip to form a TiO 2 film, onto which Au and IrO x particles were sequentially deposited, followed by cathodic and anodic reactions, respectively. The resulting Ti/TiO 2 /Au-IrO x electrode exhibited remarkable efficiency in electrochemical HER, significantly reducing the overpotential. Notably, the catalytic onset potential was recorded at −0.10 V, markedly lower than those observed for Ti, Au, and Au-IrO x electrodes individually. This improvement can be attributed to an increase in the catalytic surface area along with a synergistic effect between the TiO 2 metal sheet and the electronic state of Au, which facilitates the adsorption of hydrogen molecules onto the catalytic surface. Furthermore , the presence of IrO x supports the redox counter-reaction, enhancing overall electrochemical conversion kinetics. Electrokinetic parameters such as turnover frequency (TOF), Tafel slope, and exchange current density (j k) were calculated as 0.334 s−1, 64 mV dec−1, and 0.12 mA cm−2, respectively, outperforming other experimental electrodes in this study and approaching values comparable to those of the Pt electrode (0.354 s−1, 36 mV dec−1, and 1.13 mA cm−2, respectively). Additionally, the Ti/TiO 2 /Au-IrO x electrode exhibited lower resistance for charge transfer (Rct) during HER (0.072 kΩ) compared to other electrodes evaluated. These findings underscore the Ti/TiO 2 /Au-IrO x electrode's potential as a highly efficient catalyst for HER under acidic conditions, offering insights into the intricate mechanisms driving catalytic enhancements beyond mere surface area augmentation. • Ti/TiO2/Au-IrOx electrode is an excellent HER catalyst in an acidic medium. • The Volmer-Heyrovsky step is the rate-determining step with 64 mVdec−1 Tafel slope. • Turnover frequency is 0.334 s−1 which is very close to Pt (0.354 s−1). • The catalytic onset potential recorded at −0.10 V with 1 mA cm−2 current density. [ABSTRACT FROM AUTHOR]

The development of stable and efficient electrocatalysts based on metal-organic frameworks represents a main challenge for the overall water splitting process. Here, the ferrocene-based nickel metal-organic framework (NiFc-MOF) on nickel foam (NF) was synthesized using nickel chloride and 1, 1′-ferrocenedicarboxylic acid (FcDA) via a simple solvothermal method, and Ru nanoparticles (NPs) were reduced by FcDA and in situ grown on the surface of NiFc-MOF nanosheets. The as-prepared cactus-like Ru 0.3 @NiFc-MOF exhibits high electrocatalytic activity for hydrogen evolution reaction (HER) with a low overpotential of 25 mV@10 mA cm−2 and a Tafel slope of 45.05 mV dec−1. To reach a current density of 10 mA cm−2 for the oxygen evolution reaction (OER), a low overpotential of 210 mV was required. The assembled water electrolysis cell using Ru 0.3 @NiFc-MOF as bifunctional electrocatalysts only requires a voltage of 1.47 V to achieve a current density of 10 mA cm−2, indicating excellent electrolytic water splitting performance. In addition, the electrocatalytic activity of Ru 0.3 @NiFc-MOF's can keep the stability for 120 h Ru 0.3 @NiFc-MOF exhibits exceptional electrocatalytic performance, which can be attributed to both the intrinsic activity of Ru sites and the multiple active sites of NiFc-MOF. • Cactus-like Ru@NiFc-MOF composites were synthesized via a two-step solverthermal method. • Ru 0.3 @NiFc-MOF exhibits the excellent performances of HER (η 10 = 25 mV) and OER (η 10 = 210 mV). • The assembled water splitting device only require a voltage of 1.470 V to achieve a current density of 10 mA cm−2. [ABSTRACT FROM AUTHOR]

Using nanocatalysts to catalyze water electrolysis for hydrogen production is an ideal solution to address the energy crisis. The most well-adopted fabrication methods for nanocatalysts are tube furnace annealing, Hydrothermal method, etc., hardly satisfying the trade-off among coarsening, dispersity, and particle size due to mutual restrictions. Herein, a universal, ultrafast and facile cellulose nanometer whiskers-high temperature shock (CNW-HTS) method was reported for fabricating a library of ultrafine metal nanoparticles with uniform dispersion and narrow size distribution. The metal-anchor functional groups in CNW (i.e., –OH and –COOH) and the characteristics of the HTS method for ultrafast heating and powerful quenching synergistically contribute to the successful synthesis of metal nanoparticles. As an initial demonstration, the as-prepared Pt nanocatalyst (η10 ​mA ​cm−2 ​= ​51.8 ​mV) shows more excellent catalytic hydrogen evolution reaction (HER) performance than the Pt catalyst prepared in the tubular furnace (η10 ​mA ​cm−2 ​= ​169.4 ​mV). This rapid and universal CNW-HTS method can pave the way for nanomanufacturing to produce high-quality metal nanoparticles, thereby expanding applications of energy conversion and electrocatalysis. [ABSTRACT FROM AUTHOR]

The electrocatalytic activity of a new composite material based on η-carbide Nb3(Fe, Al)3C in the hydrogen evolution reaction from acidic and alkaline solutions is studied. The composite was obtained by spark plasma sintering of mechanically alloyed niobium, aluminum, and graphite powders in steel containers in petroleum ether, followed by etching in an alkaline solution or in a hydrofluoric acid solution. The composite consists of 78 wt % Nb3(Fe, Al)3C, 19 wt % Nb5Al3Cx, and 3 wt % graphite; it has a layered structure with a layer thickness of the Nb5Al3Cx phase of 50–70 nm. In terms of the magnitudes of overpotential in the hydrogen evolution reaction, the resulting composite is superior to undoped Nb2CTx and Nb4C3Tx. [ABSTRACT FROM AUTHOR]

Robust electrocatalytic atom pair compositions (APCs) where Nitrogen Reduction Reaction (NRR) is more enhanced over competing Hydrogen Evolution Reaction (HER) is searched for using computational studies based on Density Functional Theory based methods. Atomic pairs are anchored on mechanically and thermally stable graphene surfaces. A wide range of transition metal based atom pair compositions from 3d, 4d, and 5d groups are systematically investigated for reduction of dinitrogen molecule with lower reduction barrier as compared to HER. APR compositions of Ni–Rh with an overall limiting potential of −0.22 V, Fe–W with an overall limiting potential of −0.26 V and Co–Pt with an overall limiting potential of −0.28 V are identified as the most potent atomic pairs for enhanced nitrogen reduction reaction over the HER. Finally, the performance of most potent composition, viz., Ni–Rh is validated to be consistent with respect to their thermodynamic stability and performance within the solvent effects. [Display omitted] • Atom Pair Catalysts (APCs) are computationally evaluated for NRR over HER. • Parameters like limiting potentials, volcano plots with solvent effect studied. • Best electrocatalyst with limiting potential (U L) −0.22 V for combination of Ni–Rh. • AIMD simulations confirms the stability of pair of Ni–Rh electrocatalysts. [ABSTRACT FROM AUTHOR]