Search

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]

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]

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]

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]

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]

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 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]

Developing a cost-effective, efficient, and eco-friendly electrocatalyst made from non-noble materials for the hydrogen evolution reaction (HER) is challenging. This research paper presents an application of the nickel sulfide (Ni 3 S 2) nanowires-filled multiwalled carbon nanotubes (CNTs) synthesized on carbon cloth (CC) (Ni 3 S 2 @CNTs/CC) as an efficient HER electrocatalyst. The performance of Ni 3 S 2 @CNTs/CC as a working electrode was examined for its hydrogen evolution ability. In a 1.0 M KOH solution, Ni 3 S 2 @CNTs/CC requires cathodic overpotentials of 381 mV and 549 mV to generate current densities of 10 mA/cm2 and 100 mA/cm2, respectively. Electrochemical impedance measurements showed a low charge transfer resistance value of 3.3 Ω for Ni 3 S 2 @CNTs/CC. The evaluation of the electrochemically active surface area revealed that Ni 3 S 2 @CNTs/CC has more electrochemical active sites and a higher roughness factor than pristine CC. Most importantly, the current density of Ni 3 S 2 @CNTs/CC did not significantly degrade after 3000 CV cycles and 12 h of constant HER. These findings suggest that Ni 3 S 2 @CNTs/CC is a cost-effective, highly functional, and stable electrode material for HER in a strongly alkaline medium. [Display omitted] • Application of novel Ni 3 S 2 @CNTs/CC acting as an electrocatalyst for HER is reported for the first time. • The synthesized Ni 3 S 2 @CNTs promote water dissociation by facilitating the electron transfer process. • The enhanced catalytic HER activity of Ni 3 S 2 @CNTs/CC is attributed to the synthesized Ni 3 S 2 @CNTs on the CC substrate. • Ni 3 S 2 @CNTs/CC acts as a binder-free, flexible HER electrocatalyst. [ABSTRACT FROM AUTHOR]

The development of effective and inexpensive electrocatalysts for hydrogen evolution reaction (HER) plays a key role in future energy system. Herein, we report a series of NiS x composited with polypyrrole (PPy) hollow nanospheres on carbon papers (CPs) to promote the HER performance. The crystal phase and lattice configuration of the in-situ grown NiS x can be tuned through unipolar pulse electrodeposition. The PPy with high conductivity is conducive to prevent the NiS x from collapse and improve the stability of the HER. As a result, the optimized Ni 3 S 2 /PPy/CP electrode manifests a low overpotential of 149 mV (vs. RHE) at 10 mA cm−2, an exceptional long-term stability over 100 h, and a large electrochemically active surface area of 1173.75 cm2. Furthermore, it is found that the exposure of (110), (122) and (300) planes of Ni 3 S 2 facilitates to increase the number of active sites. The precise lattice regulation contributes to achieve high HER performance. [Display omitted] • A series of NiS x /PPy/CP composite electrocatalysts were prepared for HER. • The crystalline phase of NiS x can be tuned by controlling the lattice structure. • The (110), (122) and (300) lattice planes of Ni 3 S 2 provide rich active sites for HER. • The optimal Ni 3 S 2 /PPy/CP showed a low overpotential of 149 mV at 10 mA cm−2. • PPy is able to protect active substance from loss and improve long-term stability. [ABSTRACT FROM AUTHOR]

B atoms incorporation modulates the interfacial interaction between Ni 2 P and B,N-GC and increases the available electron density of Ni sites, resulting in decreased energy barrier, promoted electron transfer ability, and enhanced HER performance. [Display omitted] Modulation of the electronic interaction between the metal and support has been verified as a feasible strategy to improve the electrocatalytic performance of supported-type catalysts. Here, we have successfully synthesized an electrocatalyst of Ni 2 P nanoparticles (NPs) anchored on B, N co-doped graphite-like carbon nanosheets (Ni 2 P@B, N-GC), and elucidated the main mechanism by which B atoms doping enhances electrocatalytic hydrogen evolution reaction (HER) performance. The B atoms with electron-rich characteristic not only modulate the electronic structure on carbon skeleton, but also regulate the interfacial electronic interaction between Ni 2 P NPs and the carbon skeleton, which can lead to the increased available electron density of Ni sites. Such optimization is conducive to accelerating proton transfer and promoting reactive activity. As revealed, the Ni 2 P@B, N-GC catalyst with B atoms doping exhibits superior performance to the Ni 2 P@N-GC catalyst in acidic, neutral and alkaline medias. In addition, the assembled Ni(OH) 2 @B, N-GC || Ni 2 P@B, N-GC electrolyzer displays prominent overall water splitting performance in alkaline solution, which only demands 1.57 V to reach 10 mA/cm2, and in complicated natural seawater electrolyte, as low as 1.59 V. Hence, the B atoms doping strategy shows the significant enhancement for HER electrocatalysis. [ABSTRACT FROM AUTHOR]

Recently, two‐dimensional transition metal dichalcogenides (TMDs) demonstrated their great potential as cost‐effective catalysts in hydrogen evolution reaction. Herein, we systematically summarize the existing defect engineering strategies, including intrinsic defects (atomic vacancy and active edges) and extrinsic defects (metal doping, nonmetal doping, and hybrid doping), which have been utilized to obtain advanced TMD‐based electrocatalysts. Based on theoretical simulations and experimental results, the electronic structure, intermediate adsorption/desorption energies and possible catalytic mechanisms are thoroughly discussed. Particular emphasis is given to the intrinsic relationship between various types of defects and electrocatalytic properties. Furthermore, current opportunities and challenges for mechanical investigations and applications of defective TMD‐based catalysts are presented. The aim herein is to reveal the respective properties of various defective TMD catalysts and provide valuable insights for fabricating high‐efficiency TMD‐based electrocatalysts. [ABSTRACT FROM AUTHOR]

Based on the DFT calculations, two-dimensional (2D) R-graphyne has been demonstrated to have high stability and good conductivity, which can be conducive to the relevant electrocatalytic activity of the material. Different from the poor graphene, R-graphyne, which is completely composed of anti-aromatic structural units, can exhibit certain HER catalytic activity. In addition, doping the TM atoms in Group VIIIB can be considered an effective strategy to enhance the HER catalytic activity of R-graphyne. Particularly, Fe@R-graphyne, Os@R-graphyne, Rh@R-graphyne and Ir@R-graphyne can exhibit higher HER catalytic activities due to the formation of more active sites. Usually, the shorter the distance between the TM and C atoms is, the better the HER activity of the C-site is. Furthermore, doping Ni and Rh atoms of Group VIIIB can significantly improve the OER catalytic performance of R-graphyne. It can be found that ΔGO* can be used as a good descriptor for the OER activities of TM@R-graphyne systems. Both Rh@R-graphyne and Ni@R-graphyne systems can exhibit bifunctional electrocatalytic activities for HER/OER. In addition, all the relevant catalytic mechanisms are analyzed in detail. This work not only provides nonprecious and highly efficient HER/OER electrocatalysts, but also provides new ideas for the design of carbon-based electrocatalysts. [ABSTRACT FROM AUTHOR]

Electrocatalytic water splitting as a green chemical process to evolve H2 has increasingly attracted attention. Using fresh water as the proton source not only increases the cost but also significantly hinders the wide applications of electrocatalysis in H2 production. Instead, seawater is more competitive compared to fresh water from the economic aspects, but more challenging from the technical aspects. Technically, insoluble solids and chloride ions in seawater significantly affect the electrocatalytic activity and stability of catalysts. Great efforts have been spared to develop highly effective electrocatalysts for seawater splitting, and various strategies have been raised. Herein, we categorized and discussed recently reported composites applied in electrocatalytic seawater splitting. Future perspectives for the advancement of seawater-based electrocatalysts have been proposed at the end. We hope to provide some new understanding and methods for the reasonable construction of state-of-the-art electrocatalysts to tackle the challenges of seawater splitting. 摘要: 电催化水裂解作为一种绿色的制氢过程受到人们的关注。使用淡水作为电解液不仅增加了成本, 而且严重阻碍了电催化在制氢中的广泛应用。相反, 海水在经济方面比淡水更有竞争力, 但在技术方面更具挑战性。从技术上讲, 海水中的不溶性固体和氯离子会严重影响催化剂的电催化活性和稳定性。目前, 人们一直在努力开发高效的海水裂解电催化剂, 并提出了各种策略。在此, 我们对最近报道的用于电催化海水裂解的复合材料进行了分类和讨论。最后, 对海水基电催化剂的发展前景进行了展望。我们希望可以为合理构建最先进的电催化剂以应对海水分解的挑战提供一些新的认识和方法。 [ABSTRACT FROM AUTHOR]

Abstract Recently, two‐dimensional transition metal dichalcogenides (TMDs) demonstrated their great potential as cost‐effective catalysts in hydrogen evolution reaction. Herein, we systematically summarize the existing defect engineering strategies, including intrinsic defects (atomic vacancy and active edges) and extrinsic defects (metal doping, nonmetal doping, and hybrid doping), which have been utilized to obtain advanced TMD‐based electrocatalysts. Based on theoretical simulations and experimental results, the electronic structure, intermediate adsorption/desorption energies and possible catalytic mechanisms are thoroughly discussed. Particular emphasis is given to the intrinsic relationship between various types of defects and electrocatalytic properties. Furthermore, current opportunities and challenges for mechanical investigations and applications of defective TMD‐based catalysts are presented. The aim herein is to reveal the respective properties of various defective TMD catalysts and provide valuable insights for fabricating high‐efficiency TMD‐based electrocatalysts.

Trace precious metal modifying inexpensive transition metal catalyst is an effective method to optimize the activity, stability and cost of hydrogen evolution catalysts. In this feature work, self-supporting sandwich structured Co–Pt–Co/CC sheets were assembled on a carbon cloth (CC) by a simple electrodeposition/chemical displacement alternate growth method. Surprisingly, only 2.1 wt % Pt sandwich layer greatly improved the electrochemical activity of Co–Pt–Co/CC, which delivered a current density of 10 mA cm −2 at an overpotential as low as 46 mV. Importantly, its overpotential is almost 6 times lower than that of Co/CC, and is comparable to that of Pt–Co/CC. After well-tuning the sandwich layer, the optimized Co–Pt–Co/CC exhibited a higher current density and better long-term durability compared with Pt–Co/CC and Co/CC, which can be attributed to the unique tissue-structure and electronic structure optimization of the Co–Pt–Co/CC by the Pt sandwich layer. [Display omitted] • Doping trace Pt into the sandwich-like structured Co–Pt–Co/CC can significantly improve its HER performance. • The sandwich like self-supporting electrode can easily be prepared by alternating electrodeposition and impregnation. • The good hydrophilicity of Co–Pt–Co/CC surface can rapidly divert H 2 gas bubbles. [ABSTRACT FROM AUTHOR]

Finding efficient and versatile catalysts that can both produce clean energy H 2 and treat wastewater is an important matter to solve energy shortages and wastewater pollution. Herein, a feather-like NiCoP supported on NF was synthesized via the two-step hydrothermal-phosphorization process. NiCoP/NF requires only overpotentials of 44 and 203 mV to reach 10 mA cm−2 for HER and OER in 1 M KOH, respectively. Besides, NiCoP/NF requires only 1.13 V (vs RHE) to achieve 10 mA cm−2 in 1 M KOH containing 0.33 M urea. DFT calculation shows that NiCoP exhibits enhanced DOS in the Fermi level attachment, which promotes charge transfer. Subsequently, the trifunctional NiCoP/NF, for overall water splitting, requires a lower potential of 1.48 V to gain 10 mA cm−2 in 1 M KOH. For urea electrolysis, NiCoP/NF requires just 1.36 V to drive 10 mA cm−2 in 1 M KOH with 0.33 M urea. This work provides extraordinary insights into electrolytic hydrogen production and wastewater treatment through simple preparative methods. The performance of the prepared catalyst is at a high level in non-noble metal. [ABSTRACT FROM AUTHOR]

[Display omitted] • Novel deposition method: Automatic Mechanical Exfoliation (AME) enables rapid, scalable production of large-area van der Waals thin films for HER catalysts. • Superior HER performance: AME-grown ransition Metal Dichalcogenide (TMD) thin films demonstrate enhanced catalytic activity compared to conventionally produced films. • Defect engineering via gamma irradiation: Gamma irradiation significantly improves HER performance across all studied TMDs by introducing beneficial defects. • Outstanding catalyst performance: MoS 2 /NbS 2 , TiS 2 , MoSe 2 , MoS 2 , and WS 2 thin films exhibit exceptional HER activity after gamma irradiation, with low overpotentials and high turnover frequencies. • Scalable and efficient HER catalysts: AME combined with defect engineering via gamma rays offers a promising pathway for developing high-performance, scalable HER catalysts for sustainable energy applications. This study explores a novel and efficient van der Waals thin-film deposition method, called Automatic Mechanical Exfoliation (AME), and its application in hydrogen evolution reaction (HER). Compared to traditional physical deposition techniques, AME offers significant advantages: it is simpler, more cost-effective, and significantly faster, enabling the deposition of large-area (>5 cm2) coatings exhibiting superior catalytic activity towards HER. To demonstrate its versatility, we comprehensively characterized large-area TMD thin films (MoS 2 /NbS 2 , NbS 2 , TiS 2 , MoSe 2 , MoS 2 , and WS 2) using various techniques. Our AME-grown TMD thin films delivered improved HER performance, with lower Tafel slopes compared to previously reported values. To further enhance their activity, we irradiated the films with gamma radiation, leading to a remarkable improvement across all studied TMDs materials (e.g., an average increase of 30 % in exchange current density). Notably, NbS 2 thin films and MoS 2 /NbS 2 heterostructures exhibited excellent performance after irradiation, achieving low Tafel slopes (81 mV/dec and 85 mV/dec, respectively), starting overpotentials (−56 mV and −24 mV vs RHE, respectively), high exchange current densities (10.39 µA cm–2 and 625.2 µA cm–2, respectively), and turnover frequencies (0.021 s–1 and 0.95 s–1, respectively). These findings suggest that gamma irradiation can be a powerful tool for defect engineering in TMDs, creating additional active sites and demonstrably enhancing their catalytic efficiency for HER. [ABSTRACT FROM AUTHOR]

• Mo 132 polyoxometalate acts as precursor to synthesize electrocatalyst. • Ni/MoN@NC and Ni/NiO@NC are synthesized at different temperature. • Ni/MoN@NC shows η 10 of 94 mV for HER. • Ni/NiO@NC shows η 10 of 1.41 V for UOR. Electrochemical water decomposition is an efficient and environmentally friendly method for producing hydrogen. Because of the high voltage required for water electrolysis, using anodic urea oxidation process (UOR) to replace the oxygen evolution reaction can significantly cut energy usage. In this paper, hydrogen evolution reaction (HER) and urea oxidation process (UOR) electrocatalysts were synthesized by one-step carbonization using giant polyoxomolybdate cluster Mo 132 and triethylamine at different temperatures. Ni/MoN@NC obtained at 800 °C shows good HER effect in the acidic electrolyte, an overpotential of 94 mV can provide the current density of 10 mA cm−2. Ni/NiO@NC obtained by calcination at 400 °C exhibits good UOR performance, in which the potential is 1.41 V when the current density is 10 mA cm−2. Efficient HER performance depends on the synergy of Ni and MoN. The highly efficient UOR is derived from the hierarchical structure of Ni and NiO. Furthermore, the porous structure also enhances the full contact between electrolyte and active sites, the catalytic performance of the catalyst was improved benefit to improve the catalytic activity. This work affords a general approach to simply synthesize efficient hydrogen producing materials for HER and small molecules oxidation fields. In this study, triethylamine was used as a carbon source to mix with Mo 132 and metal Ni2+.After centrifugation and drying, green powders were obtained, and then calcined at 800 °C and 400 °C to obtain catalysts for high-efficiency HER and UOR, Ni/MoN@NC and Ni/NiO@NC. [Display omitted] [ABSTRACT FROM AUTHOR]

Designing and synthesizing high-activity, durable, and low-cost catalysts for the electrochemically transformation of water to hydrogen are vitally important to future energy systems. Herein, a simple but effective strategy for manganese-metal-heteroatom doping is adopted to intrinsically elevate the electrocatalytic activities of SnS 2 nanosheets by a facile two steps hydrothermal-sulfurization approach. Electrocatalytic hydrogen evolution (HER) performance of Mn–SnS 2 nanosheets grown on 3D nickel foam (Mn–SnS 2 /NF) is efficiently optimized since the dopants and defects endow the Mn–SnS 2 /NF vast active sites. An overpotential as low as 71 mV is required to drive a current density of 10 mA/cm2 with a low Tafel slope of 72 mV dec−1 in alkaline environment (1 M KOH). In addition, the Mn–SnS 2 /NF exhibits prominent stability in 1 M KOH electrolyte, which is an indispensable index for the potential HER electrocatalysts. The present work demonstrates that the heteroatom manganese doping strategy renders a meaningful route for synthesizing cost-efficient HER electrocatalysts in alkaline condition. [Display omitted] • The Mn–SnS 2 /NF nanosheets had rich defects induced by Mn dopants. • The optimal atomic ratio of Mn dopants was 6.9%. • The Mn dopants and defects contributed the drastically enhanced electrochemical HER activity. • Mn–SnS 2 /NF only required an overpotential as small as 71 mV to drive a current density of 10 mA cm−2. • Mn–SnS 2 /NF had exhibited remarkable stability and long-term durability of 24h. [ABSTRACT FROM AUTHOR]

Hydrogen is considered a promising clean energy vector with the features of high energy capacity and zero-carbon emission. Water splitting is an environment-friendly and effective route for producing high-purity hydrogen, which contains two important half-cell reactions, namely, the anodic oxygen evolution reaction (OER) and the cathodic hydrogen evolution reaction (HER). At the heart of water splitting is high-performance electrocatalysts that efficiently improve the rate and selectivity of key chemical reactions. Recently, perovskite oxides have emerged as promising candidates for efficient water splitting electrocatalysts owing to their low cost, high electrochemical stability, and compositional and structural flexibility allowing for the achievement of high intrinsic electrocatalytic activity. In this review, we summarize the present research progress in the design, development, and application of perovskite oxides for electrocatalytic water splitting. The emphasis is on the innovative synthesis strategies and a deeper understanding of structure–activity relationships through a combination of systematic characterization and theoretical research. Finally, the main challenges and prospects for the further development of more efficient electrocatalysts based on perovskite oxides are proposed. It is expected to give guidance for the development of novel non-noble metal catalysts in electrochemical water splitting. [ABSTRACT FROM AUTHOR]

Graphitic carbon nitride (g-C 3 N 4) has emerged as a promising eco-friendly material for catalysis and sensing applications due to their unique properties. However, limitations like low specific surface area, insufficient light absorption, and poor conductivity hinder their broader usability. Elemental doping has been established as an effective approach to modify the electronic structure and bandgap of g-C 3 N 4 thus significantly expanding its light-responsive range for enhanced charge separation. This work reports on the fabrication of cost-effective and stable g-C 3 N 4 and cobalt-doped g-C 3 N 4 (Co@g-C 3 N 4) via a simple one-step calcination process. The humidity sensing performance of both g-C 3 N 4 and Co@g-C 3 N 4 was evaluated across a broad humidity range (7 % - 94 % RH) at various testing frequencies. The results demonstrated good reversibility with Co@g-C 3 N 4 exhibiting superior performance compared to pristine g-C 3 N 4. Furthermore, the synthesized materials were assessed for their suitability as photoelectrochemical water splitting catalysts for hydrogen production, representing a step towards energy-efficient fuel cells. Notably, Co@g-C 3 N 4 displayed enhanced performance with a lower onset potential (420 mV) and a lower Tafel slope (65.4 mV dec-1) for the hydrogen evolution reaction (HER) compared to undoped counterparts. Additionally, Co@g-C 3 N 4 nanorods exhibited remarkable performance for the oxygen evolution reaction (OER), showcasing a lower onset potential (1.505 V) and a considerably low overpotential (270 mV), surpassing numerous reported electrocatalysts and even rivaling precious-metal-based ones. Finally, enhanced photocatalytic activities for organic dyes degradation were recorded for the mentioned materials. Therefore, g-C 3 N 4 and related materials have great potential for their industrial electrochemcial applications. • Developed cobalt-doped graphitic carbon nitride (Co@g-C 3 N 4) using a one-step hydrothermal process. • Superior humidity sensing performance of (Co@g-C 3 N 4) across a wide range was achieved. • Co@g-C 3 N 4 showed enhanced photoelectrochemical water splitting performance. • Co@g-C 3 N 4 exhibited lower onset potential and Tafel slope for hydrogen evolution reaction (HER). [ABSTRACT FROM AUTHOR]

• MoS 2 /C are promising non-noble alternatives to replace Pt for HER. • MoS 2 /C is stable in HER conditions as minimal Mo dissolution is reported. • Excursions at anodic potential are detrimental to HER activity. • Continuous exfoliation of the 2D MoS 2 stacked layers is the main degradation mechanism at high electrode potentials. • Start/stop events should be properly managed to avoid excursions above 0.7V RHE. Molybdenum dichalcogenides (MoS 2) are promising non-noble alternatives to replace platinum (Pt) for Hydrogen Evolution Reaction (HER) electrocatalysis in Proton Exchange Membrane Water Electrolyzers (PEMWE). The knowledge acquired on this class of catalyst for hydrodesulfurization (HDS) reactions has enabled significant advances in designing active MoS 2 for HER. However, the stability of MoS 2 in the dynamic operating conditions of a PEMWE coupled to renewable energy sources is often overlooked in the literature and is the focus of the present work. Herein, using nano slabs of 2H MoS 2 supported on high surface area carbon, we dynamically monitored Mo dissolution trends both under HER conditions and at more anodic potentials to mimic start-ups and shut-downs of a PEMWE device. We report minimal Mo dissolution under HER conditions but it continuously increased with higher electrode potentials. In particular, Mo dissolution peaked during the irreversible oxidation from Mo(IV) to Mo(VI) starting at E = 0.7 V RHE which in turn fully annihilates HER activity. Since no change in Mo and S surface composition was observed, the decline in HER activity was attributed to the continuous exfoliation of the 2D MoS 2 stacked layers induced by oxidation/dissolution of Mo. Additionally, our findings indicate that Mo cations can redeposit onto the cathode catalytic layer, forming a Mo blue film primarily composed of Mo(VI) species. This redeposition hampers HER performance by blocking catalytic sites and diminishing the catalyst's overall efficiency. These insights demonstrate the need to avoid excursions above E = 0.6 V RHE for the safe use of MoS 2 cathode catalyst in PEMWE. [ABSTRACT FROM AUTHOR]

Based on the DFT calculations, two-dimensional (2D) R-graphyne has been demonstrated to have high stability and good conductivity, which can be conducive to the relevant electrocatalytic activity of the material. Different from the poor graphene, R-graphyne, which is completely composed of anti-aromatic structural units, can exhibit certain HER catalytic activity. In addition, doping the TM atoms in Group VIIIB can be considered an effective strategy to enhance the HER catalytic activity of R-graphyne. Particularly, Fe@R-graphyne, Os@R-graphyne, Rh@R-graphyne and Ir@R-graphyne can exhibit higher HER catalytic activities due to the formation of more active sites. Usually, the shorter the distance between the TM and C atoms is, the better the HER activity of the C-site is. Furthermore, doping Ni and Rh atoms of Group VIIIB can significantly improve the OER catalytic performance of R-graphyne. It can be found that ΔGO* can be used as a good descriptor for the OER activities of TM@R-graphyne systems. Both Rh@R-graphyne and Ni@R-graphyne systems can exhibit bifunctional electrocatalytic activities for HER/OER. In addition, all the relevant catalytic mechanisms are analyzed in detail. This work not only provides nonprecious and highly efficient HER/OER electrocatalysts, but also provides new ideas for the design of carbon-based electrocatalysts.

The electrocatalytic performance of Et@PZn and LPOM@EtPZn for HER and OER in alkaline media was systematically assessed. Notably, LPOM@EtPZn exhibited a lower overpotential for HER and OER than Et@PZn indicating its superior kinetics, which was further confirmed by Tafel slope values. So, LPOM@EtPZn showed enhanced catalytic efficiency than Et@PZn due to the incorporation of POM into a layer structure creating synergistic effects. [Display omitted] • In this article we have reported. • Et@PZn COF was synthesized from metalloporphyrin and ethylenediamine. • Lindqvist POM was incorporated into COF's cavities, resulting LPOM@EtPZn framework. • Et@PZn and LPOM@EtPZn were tested for HER and OER in an alkaline medium. • LPOM@EtPZn exhibited lower overpotential than Et@PZn indicating superior kinetics. An effective method for producing valuable fuels is electrocatalytic water dissociation, which involves the hydrogen evolution reaction (HER) and the oxygen evolution reaction (OER). So, the development of new electrocatalysts for enhancing these processes is expected to minimize their overpotentials and increase the accessibility of their practical applications. The multifunctional properties of porphyrins and polyoxometalate (POMs) can help energy conversion devices. This study presents the synthesis of a novel metalloporphyrin and ethylenediamine-containing covalent organic framework (Et@PZn) and its successful incorporation of Lindqvist POM into the COF's cavities, resulting in the LPOM@EtPZn framework. Both frameworks underwent comprehensive structural and morphological characterizations. The electrocatalytic performance in alkaline media was systematically assessed. Notably, LPOM@EtPZn exhibited a lower overpotential for HER and OER than Et@PZn indicating its superior kinetics, which was further confirmed by Tafel slope values of about 115 mV dec−1 and 55 mV dec−1 for LPOM@EtPZn which found better than that of Et@PZn of about 161 mV dec−1 and 108 mV dec−1 for HER and OER respectively. LPOM@EtPZn also showed best overpotential than standard 20 %Pt/C electrode for HER. Electrochemical investigations, including electroactive surface area (ECSA) measurement and electrochemical impedance spectroscopy (EIS), also confirmed the charge transfer advantages of LPOM@EtPZn. These findings underscore the potential of LPOM@EtPZn as a versatile and efficient electrocatalyst for diverse applications, in advancing renewable energy technologies. [ABSTRACT FROM AUTHOR]

The design of nanostructures and the adjustment of components are very important to improve the performance of hydrogen evolution electrocatalysts. In this paper, Ni, W and Mo trimetallic catalysts are studied from the aspects of morphology, structure and electronic transfer, and a better combination of hydrogen reaction efficiency is obtained. The W/Mo co-doped nickel sulfide electrocatalyst was synthesized on Ni foam by one-step hydrothermal method. As anticipated, the individual incorporation of either tungsten (W) or molybdenum (Mo) into the electrocatalyst did not yield satisfactory enhancements in hydrogen evolution reaction (HER) performance. However, when both W and Mo were co-doped onto the electrocatalyst, a significant improvement in catalyst material performance was observed. Hence, the coexistence of W and Mo is the key to improve HER electrocatalytic activity. In 1 M KOH solution, the W/Mo-Ni 3 S 2 /NF electrocatalyst exhibited exceptional HER activity with an overpotential of only 136 mV at a current density of 10 mA·cm−2 and demonstrated excellent cycle stability exceeding 20 hours. In this paper, the strategy of bimental co-doping composite is adopted to adjust the structure of nickel sulfide, which provides reference value for the design of reasonable and efficient HER electrocatalyst. • Due to the combined action of tungsten and molybdenum elements, the electrocatalyst forms a unique nanowire structure. • The combined action of bimetallic elements results in an electrode material with superhydrophilic and aerophobic properties. • The nanowire structure provides greater roughness to the surface of the electrode material, increasing the exposed active sites, thereby improving the overall performance of the electrocatalyst and maintaining better stability in long-term testing. [ABSTRACT FROM AUTHOR]

In this work, we report several Ga intercalated NiCoP nanoneedle catalysts. The prepared catalyst drives HER with an overpotential of 348 mV at 500 mA cm−2 and 270 mV at 100 mA cm−2 for OER. [Display omitted] • The findings shed light on the effectiveness of element intercalation strategy in improving catalyst performance. It indicates that the introduction of ions increases the exposed active sites and accelerates the species reconstruction. • We report several Ga-NiCoP nanoneedle (Ga-NiCoP) catalysts through Ga ion intercalation strategy. The Ga intercalated NiCoP possesses excellent catalytic activity. • The prepared catalyst drives HER with an overpotential of 348 mV at 500 mA cm−2 and 270 mV at 100 mA cm−2 for OER. • As a bifunctional electrocatalyst, the results demonstrate excellent stability and low cell voltage in a two-electrode system. it achieves a cell voltage of 1.47 V at current density 10 mA cm−2 in a two-electrode system and maintains stability for 150 h. Developing non-precious catalysts with optimal catalytic performance is very crucial for sustainable energy-related systems. However, the sluggish kinetics and low efficiency limits their practical applications. Herein, we report several Ga intercalated NiCoP nanoneedle (Ga-NiCoP) catalysts. It indicates that the introduction of Ga ions increases the exposed active sites and accelerates the species reconstruction. The prepared catalyst drives HER with an overpotential of 348 mV at 500 mA cm−2 and 270 mV at 100 mA cm−2 for OER. Meanwhile, it achieves a cell voltage of 1.47 V at current density 10 mA cm−2 in a two-electrode system and maintains stability for 150 h. This work provides a general approach to fabricate some other non-precious metal electrocatalysts to produce hydrogen. [ABSTRACT FROM AUTHOR]

Metal-organic frameworks (MOFs) based derivatives have been extensively used as electrocatalysts in hydrogen evolution reaction (HER) due to the tunable structures, adjustable pore sizes and large specific surface areas. Hereto, a new Cu-MOF (MOF-517) constructed by sulfur-containing and flexible mixed ligands was prepared via hydrothermal synthesis method using Cu ions as the center. MOF-517 is then used as precursor material to obtain the hydrogen evolution electrocatalyst (Cu/Cu 2 S@C) through a one-step high-temperature calcination process. Cu/Cu 2 S@C shows favorable HER activity in both alkaline and acidic solutions, with lower overpotentials of 137 and 196 mV at current density up to 10 mA cm−2. Meanwhile, Cu/Cu 2 S@C shows excellent electrocatalytic stability for 24 h. This work provides a certain experimental contribution to the synthesis of copper-based MOF-derived sulfides for renewable and clean energy generation applications. A new Cu-MOF (MOF-517) constructed by sulfur-containing and flexible mixed ligands was prepared via hydrothermal synthesis method using Cu ions as the center. MOF-517 is then used as precursor material to obtain the hydrogen evolution electrocatalyst (Cu/Cu 2 S@C) through a one-step high-temperature calcination process. Cu/Cu 2 S@C shows favorable HER activity and excellent electrocatalytic stability. [Display omitted] • A new Cu-MOF (MOF-517) constructed by sulfur-containing and flexible mixed ligands using Cu ions as the center. • Cu/Cu 2 S@C shows favorable HER activity and excellent electrocatalytic stability for 24 h. • This work provides a certain experimental contribution to the synthesis of copper-based MOF-derived sulfides for HER. [ABSTRACT FROM AUTHOR]

Highly active, stable and affordable hydrogen evolution reaction (HER) electrocatalysts are intensively needed for global energy conversion systems. Carbon-supported ruthenium (Ru)-based electrocatalysts have been rising stars in recent years and the pursuit of higher activity has arisen intensive research interest. Herein, a novel electrocatalyst with cellulose nanofibers containing abundant carboxyls and hydroxyls as the carbon source to anchor Ru nanoparticles (Ru/NC) was designed and synthesized. Benefiting from the anchoring and dispersion of the carbon substrate to the Ru nanoparticles and the synergistic interaction between the different components, the obtained Ru/NC exhibited optimal HER activity in all the corresponding contrast electrocatalysts, with low overpotentials of 16 mV, 22 mV, and 46 mV to attain 10 mA cm−-2 in 1.0 M KOH, 0.5 M H 2 SO 4 and 1.0 M KOH + seawater, respectively. Further, the Tafel slope of Ru/NC in alkaline seawater indicated that its HER process followed a Volmer-Tafel mechanism. Additionally, the synthesized Ru/NC also displayed excellent stability in different electrolytes. This work will provide a novel and interesting insight into the fabrication of advanced carbon-supported electrocatalysts with resource-rich biomass as cost-effective carbon source. [ABSTRACT FROM AUTHOR]

• Ultrasmall molybdenum carbide α − MoC 1 − x nanoparticles (1.6 nm) and a hybrid material composed of α − MoC 1 − x and reduced graphene oxide (rGO/ α − MoC 1 − x ) were synthesized by a one-pot oleylamine-mediated at a low temperature. • The materials were evaluated as electrocatalysts for the hydrogen evolution reaction (HER) in the acid medium, evidencing quite large activity for the HER. • The synthesis route is simple with low cost and energy consumption, showing a high potential to develop efficient and inexpensive catalysts for HER. Ultrasmall molybdenum carbide α − MoC 1 − x nanoparticles (1.6 nm) and the hybrid material rGO/ α − MoC 1 − x supported in reduced graphene oxide (rGO) were synthesized by a one-pot oleylamine-mediated route at low-temperature (613 K). They were evaluated as electrocatalysts for the hydrogen evolution reaction (HER) in the acid medium after surface cleaning with an ethanol-acetic acid solution. The electrocatalysts were also thermal treated (N 2 flow, 773 K/30 min) and compared with untreated ones. Quite large HER activity was observed for the α − MoC 1 − x compared with the rGO/ α − MoC 1 − x and rGO/ α − MoC 1 − x − 773. In addition, after cycling, all catalysts showed considerable performance improvement assigned to removing residual oleylamine molecules from the electrocatalyst's surface. Compared to the unsupported sample, the lower catalytic activity in the supported materials was attributed to the ultrasmall carbide nanoparticles oxidation increases. The route is simple, with low costs and energy consumption, showing a high potential to develop efficient electrocatalysts for HER. [Display omitted] [ABSTRACT FROM AUTHOR]

Herein, we presented a simple two-step hydrothermal method to fabricate noble-metal-free 3D net-like Ni 3 (VO 4) 2 ultrathin nanosheets coupled with the MoS 2 @CFC interface. Benefiting from the reciprocally binding structure and interfacial coupling effects between Ni 3 (VO 4) 2 nanosheet and MoS 2 @CFC, the catalytically active area was expanded, and the intrinsic activity toward HER was significantly improved. [Display omitted] • Ni 3 (VO 4) 2 with 3D net-like structure was constructed on the MoS 2 nanosheets. • The interface coupling structure was formed between MoS 2 and Ni 3 (VO 4) 2. • This work provides new perspectives to construct efficient electrocatalysts. The use of cheap and efficient electrocatalyst for the production of hydrogen is the key to solving the current energy crisis. Herein, we used a two-step hydrothermal process to fabricate noble-metal-free 3D net-like Ni 3 (VO 4) 2 ultrathin nanosheets coupled with MoS 2 @CFC interface. Unlike the traditional two-dimensional composite materials, Ni 3 (VO 4) 2 ultrathin nanosheets intersect with MoS 2 nanosheets grown on CFC in a 3D net-like structure (Ni 3 (VO 4) 2 /MoS 2 @CFC). Due to the mutual combination of structures and the interfacial coupling cooperation effect between Ni 3 (VO 4) 2 nanosheet and MoS 2 @CFC, the catalytically active area was expanded, and the intrinsic activity toward HER was significantly improved. Ni 3 (VO 4) 2 /MoS 2 @CFC showed high activity at the industrial temperature (75 °C), with an overpotential of 77 mV (10 mA/cm2) and a 65 mV/dec Tafel slope. This material showed good stability at 0.5 M H 2 SO 4. This work provides a heterostructure scheme for the construction of a novel noble metal-free electrocatalyst to promote hydrogen evolution reaction. [ABSTRACT FROM AUTHOR]

The development of cost-effective non-precious metal electrocatalysts is a major challenge for water splitting applications, but it is important for the realization of renewable energy systems. Alloying has proved an effective way to design metal-based electrocatalysts, and by controlling the annealing temperature, the surface morphology and crystallinity of the alloy can be tuned to control the hydrogen evolution reaction (HER) performance. In this work, with a simple coprecipitation method, we have prepared Co 2 FeAl alloys at different annealing temperatures (550 °C–670 °C), which exhibit excellent crystallinity and electrocatalytic performance for HER in alkaline solution. Among all conditions, the Co 2 FeAl alloys prepared at 620 °C shows the better crystallinity and the higher purity, and it could achieve a low overpotential of 149 mV at 10 mA cm−2 in alkaline solution. The overpotential demonstrates persistent stability with only 3 mV change after over 1000 cycles. Both density functional theory (DFT) calculations and experimental results revealed that alloying optimizes the electronic structure near the Fermi surface of the system, improving the electron transport efficiency and enhancing the catalytic activity. These Co 2 FeAl alloys are appealing candidates for high-performance alkaline HER electrocatalytic electrodes in water electrolysis due to their outstanding electrocatalytic properties. We demonstrate that the efficient electrocatalytic activity is due to high temperature annealing, along with the synergistic effect of alloying, lead to the surface structure and electronic structure of the alloy have changed. This strategy enables the Co 2 FeAl alloy electrocatalyst to achieve a low overpotential of 149 mV at 10 mA cm−2 in alkaline solution. [Display omitted] • Co 2 FeAl Alloy is prepared by facile coprecipitation method. • High temperature annealing to adjust the crystal plane orientation of alloys. • It could achieve a low overpotential of 149 mV at 10 mA cm−2 in alkaline solution. • It shows highly efficient electrocatalytic activity for HER while remaining stable/durable. • DFT calculations revealed that it optimizes the electronic structure near the Fermi surface. [ABSTRACT FROM AUTHOR]

The hydrogen evolution reaction (HER) is a developing and promising technology to deliver clean energy using renewable sources. Presently, electrocatalytic water (H2O) splitting is one of the low-cost, affordable, and reliable industrial-scale effective hydrogen (H2) production methods. Nevertheless, the most active platinum (Pt) metal-based catalysts for the HER are subject to high cost and substandard stability. Therefore, a highly efficient, low-cost, and stable HER electrocatalyst is urgently desired to substitute Pt-based catalysts. Due to their low cost, outstanding stability, low overpotential, strong electronic interactions, excellent conductivity, more active sites, and abundance, transition metal tellurides (TMTs) and transition metal phosphides (TMPs) have emerged as promising electrocatalysts. This brief review focuses on the progress made over the past decade in the use of TMTs and TMPs for efficient green hydrogen production. Combining experimental and theoretical results, a detailed summary of their development is described. This review article aspires to provide the state-of-the-art guidelines and strategies for the design and development of new highly performing electrocatalysts for the upcoming energy conversion and storage electrochemical technologies.

Hydrogen is a carbon-free alternative energy source for use in future energy frameworks with the advantages of environment-friendliness and high energy density. Among the numerous hydrogen production techniques, sustainable and high purity of hydrogen can be achieved by water electrolysis. Therefore, developing electrocatalysts for water electrolysis is an emerging field with great importance to the scientific community. On one hand, precious metals are typically used to study the two-half cell reactions, i.e., hydrogen evolution reaction (HER) and oxygen evolution reaction (OER). However, precious metals (i.e., Pt, Au, Ru, Ag, etc.) as electrocatalysts are expensive and with low availability, which inhibits their practical application. Non-precious metal-based electrocatalysts on the other hand are abundant with low-cost and eco-friendliness and exhibit high electrical conductivity and electrocatalytic performance equivalent to those for noble metals. Thus, these electrocatalysts can replace precious materials in the water electrolysis process. However, considerable research effort must be devoted to the development of these cost-effective and efficient non-precious electrocatalysts. In this review article, we provide key fundamental knowledge of water electrolysis, progress, and challenges of the development of most-studied electrocatalysts in the most desirable electrolytic solutions: alkaline water electrolysis (AWE), solid-oxide electrolysis (SOE), and proton exchange membrane electrolysis (PEME). Lastly, we discuss remaining grand challenges, prospect, and future work with key recommendations that must be done prior to the full commercialization of water electrolysis systems. • Presents key fundamental knowledge of water electrolysis. • Progress and challenges of the development of electrocatalysts in the most desirable water electrolytic process. • Discussion on grand challenges, prospect, and key recommendations to the commercialization of water electrolysis systems. [ABSTRACT FROM AUTHOR]

Pyrolyzed cobalt-nitrogen-carbon (Co–N-C) systems are considered as promising Pt-free electrocatalysts for oxygen reduction reaction (ORR) and hydrogen evolution reaction (HER). Here, we studied the possibility of using poly-5-aminoindole together with graphene oxide, multilayer graphene (MLG), or nitrogen-doped MLG (N-MLG) for the formation of Co–N-C electrocatalysts for both ORR and HER in acid electrolyte. Using 5-aminoindole with ammonium persulfate instead of pre-prepared polymer allows to simplify the synthesis of Co–N-C electrocatalysts, but causes the presence of Co9S8 particles in their composition. It was found that type of graphene-like precursor affects composition catalysts and the ratio of active sites, which leads to differences in their catalytic performance towards ORR and HER. The best efficiency of electrocatalyst derived from N-MLG for both ORR (onset potential of 795 mV, half-wave potential of 688 mV, and a Tafel slope of 73 mV/dec) and HER (overpotential of 207 mV at the current density of 10 mA/cm2, and a Tafel slope of 69 mV/dec) is largely attributed to the highest content of pyridinic nitrogen in its composition, which is responsible for the formation of CoNx active sites. The obtained results allow to conclude that the same active sites of the prepared catalysts are participate in both HER and ORR. [ABSTRACT FROM AUTHOR]

The urea solution electrolysis has become more attractive than water splitting, because it not only produces clean H 2 via the cathodic hydrogen evolution reaction (HER) with lower cell voltage, but also treats sewage containing urea through anodic urea oxidation reaction (UOR). However, lack of efficient electrocatalysts for HER and UOR has limited its development. Herein, hairy sphere -like Ni 9 S 8 /CuS/Cu 2 O composites were synthesized on nickel foam (NF) in situ by a two-step hydrothermal method. The Ni 9 S 8 /CuS/Cu 2 O/NF exhibited good electrocatalytic activity for both HER (−0.146 V vs. RHE to achieve 10 mA cm−2) and UOR (1.357 V vs. RHE to achieve 10 mA cm−2). Based on the bifunctional properties of Ni 9 S 8 /CuS/Cu 2 O/NF, a dual-electrode urea solution electrolytic cell was constructed, which only needed a low voltage of 1.47 V to reach a current density of 10 mA cm−2, and displayed a good stability during a 20-h test. In addition, the reason for the good catalytic activity of Ni 9 S 8 /CuS/Cu 2 O/NF was analyzed and the UOR mechanism was discussed in detail. Our research shows that Ni 9 S 8 /CuS/Cu 2 O/NF is a very promising low-cost dual-function electrocatalyst, which can be used for high-efficiency electrolysis of urea solution to produce hydrogen and treat wastewater. [Display omitted] • The hairy sphere-like Ni 9 S 8 /CuS/Cu 2 O/NF was synthesized by a simple two-step hydrothermal method. • Ni 9 S 8 /CuS/Cu 2 O/NF is an excellent bifunctional electrocatalyst for both HER and UOR. • The symmetric dual-electrode urea solution electrolytic cell only needs a voltage of 1.47 V to reach 10 mA cm−2. [ABSTRACT FROM AUTHOR]

• Defective MnCo-LDH nanoflowers is obtained by simple hydrothermal method. • The MnCo-LDH shows well 3D nanostructure and bimetallic defective vacancy. • The activity of MnCo-LDH is excellent as HER and OER bifunctional catalysts. • The MnCo-LDH show high catalytic activity and stability in potential application. Manganese-cobalt layered double hydroxide (MnCo-LDH) is a kind of layered bimetallic hydroxide with good catalytic performance and stability for water decomposition. In this paper, a series of defective MnCo-LDH materials with different Mn/Co molar ratio was prepared by hydrothermal method. The results show that the MnCo-nanoflowers containing Mn and Co elements are successfully prepared, and all of them contain N, O, Mn and Co elements. The hydrogen evolution reaction (HER) catalytic performance of Co vacancy (V Co)-MnCo-LDH is better than that of commercial electrode Pt/C, and oxygen evolution reaction (OER) catalytic performance of Mn vacancy (V Mn)-MnCo-LDH is better than that of commercial electrode RuO 2. Two-electrode overall water splitting (OWS) test showed that the overpotential required by V Mn -MnCo-LDH/NF||V Co -MnCo-LDH/NF and Pt/C/NF||RuO 2 /NF were 1.56 V and 1.72 V respectively at the current density of 10 mA cm−2, and the catalytic activity of the prepared defective MnCo-LDH is excellent bifunctional electrocatalysts for both HER and OER. [ABSTRACT FROM AUTHOR]

• Electrochemical studies on σ-acetylide complexes. • Hydrogen evolution reaction (HER) studies using acetic acid as proton source. • Studies on mechanistic pathways using density functional theory (DFT) calculation. Molecular hydrogen (H 2) is a potential alternative to fossil fuels since it is a green energy source with high energy density and non-polluting combustion materials. We present herein the electrochemical properties and hydrogen evolution reaction (HER) ability of two Pt(II) diynes (Pt-Sb-Pt & Sb-Pt-Sb) bearing stilbene unit. Both complexes catalyzed the HER in acidic media. In addition, density functional theory (DFT) calculation was carried out at B3LYP/LANL2DZ level of theory in gas phases as well as in the solvent (DMF) to delineate the possible mechanism of HER. We demonstrated that the studied Pt(II) electrocatalysts shift the reduction potential noticeably. However, no apparent role of photo-switchable stilbene fragment on electrolysis was observed and the presence of ethynyl moiety was necessary for stabilization of the metal center. To the best of our knowledge, this is the first study highlighting the electrocatalytic HER by platina-ynes. [ABSTRACT FROM AUTHOR]

Constructing high-performance catalyst for hydrogen evolution reaction (HER) is the effective way to eliminate energy crisis. Reasonable engineering of heterointerfaces can effectively create more active sites and promote electron transfer resulting in improvement in the catalytic activity. In this work, we synthesize the well-defined molybdenum carbides and tungsten carbides nano-heterostructure (Mo 2 C/W 2 C) by carbonization with CH 4 /H 2 at 800 °C showing excellent HER activity, fast kinetics and electrochemical stability in both alkaline and acidic electrolytes. Mo 2 C/W 2 C requires only 140 and 132 mV overpotentials to reach catalytic current density of 10 mA cm−2 in 0.5 M H 2 SO 4 and 1 M KOH electrolyte, respectively. Tafel slope is as low as 51 and 76 mV dec−1 in 0.5 M H 2 SO 4 and 1 M KOH comparable to the benchmarked Pt/C. Moreover, Mo 2 C/W 2 C exhibits a superior stability with slight deterioration in HER performance after 5000 potential cycles. This work elucidates that the rational construction of heterointerfaces is favorable for design of efficient non-noble metal electrocatalyst for HER catalysis. Image 1 • Mo 2 C/W 2 C heterogeneous electrocatalyst is successfully synthesized. • The overpotential is 140 mV for Mo 2 C/W 2 C to deliver 10 mA cm−2 in acidic medium. • Mo 2 C/W 2 C requires 132 mV overpotential to reach 10 mA cm−2 in alkaline medium. [ABSTRACT FROM AUTHOR]

Electrocatalytic water splitting is one of the most favorable methods for industrial-scale hydrogen production, but high cost and scarcity of commercially available noble metals restrict its application for hydrogen evolution reaction (HER). It is challenging to develop efficient non-noble metal-based electrocatalysts for HER. Herein, a Ni–Cr was doped on Copper foam (CF) substrate by adopting a simple annealing process. The high electrocatalytic efficiency for HER was achieved with Ni–Cr@CF electrode in strong basic medium with a lower overpotential of 144 mV to gain a current density of 10 mA cm−2 with a small Tafel slope of 88 mV dec−1. After surface modification, the CF substrate exhibits that the entire surface was uniformly covered with Ni–Cr species ensuring the fast reaction kinetics due to the efficient electron transfer process between the substrate and active catalyst. Moreover, the Ni–Cr@CF electrode exhibits excellent stability up to 2000 cycles under the strong basic medium. The hierarchical surface structure of Ni–Cr on conductive Cu substrate has been explored as robust electrocatalyst for hydrogen evolution reaction. Image 1 •Hierarchical structure of Ni–Cr on Copper foam (CF) substrate was attained. •The high electrocatalytic efficiency for HER was achieved with Ni–Cr@CF electrode. •Ni–Cr@CF electrode exhibited excellent stability up to 2000 cycles. •Ni–Cr@CF electrode proved as robust electrocatalyst for HER. [ABSTRACT FROM AUTHOR]

MoS2 have recently emerged as alternatives to noble metals as electrocatalysts for the hydrogen evolution reaction (HER) owing to their abundance and low cost. Considering the shortcomings of MoS2, including insufficient active sites, inert basal plane, and poor conductivity, the electrocatalytic hydrogen evolution properties of MoS2 can be improved in three ways: activating the inert basal plane to improve intrinsic activity, increasing active edge sites, and improving the conductivity. Defects can adjust the surface electronic structure of the crystal to bring the hydrogen adsorption free energy closer to zero. Therefore, current research has mainly used S‐vacancies to activate the inert basal surface of MoS2; used edge defects to increase the number of active sites; and used defective conductive carbon supports to improve the conductivity of MoS2‐based catalysts. This review introduces researches on improving the performance of MoS2 for HER by considering the purpose, characterization, and preparation of defects. [ABSTRACT FROM AUTHOR]

Designing cost‐effective and efficient electrocatalysts plays a pivotal role in advancing the development of electrochemical water splitting for hydrogen generation. Herein, multifunctional active‐center‐transferable heterostructured electrocatalysts, platinum/lithium cobalt oxide (Pt/LiCoO2) composites with Pt nanoparticles (Pt NPs) anchored on LiCoO2 nanosheets, are designed towards highly efficient water splitting. In this electrocatalyst system, the active center can be alternatively switched between Pt species and LiCoO2 for hydrogen evolution reaction (HER) and oxygen evolution reaction (OER), respectively. Specifically, Pt species are the active centers and LiCoO2 acts as the co‐catalyst for HER, whereas the active center transfers to LiCoO2 and Pt turns into the co‐catalyst for OER. The unique architecture of Pt/LiCoO2 heterostructure provides abundant interfaces with favorable electronic structure and coordination environment towards optimal adsorption behavior of reaction intermediates. The 30 % Pt/LiCoO2 heterostructured electrocatalyst delivers low overpotentials of 61 and 285 mV to achieve 10 mA cm−2 for HER and OER in alkaline medium, respectively. [ABSTRACT FROM AUTHOR]

Gas purging during electrodeposition has significant influence on microstructures and compositions of materials. Co−Mn LDH was electrodeposited on Ni foam without gas purging. In contrast, the product grown by electrodeposition with N2 purging changes to Co9S8/Co3O4 heterostructure with the assistance of annealing. This remarkable distinction is mainly due to the decrease of concentration of hydroxide ions (produced by the reduction of NO3−) near electrode surface where the ion transport is remarkably enhanced by N2 purging. The heterostructure has shown superior performance for water splitting, especially for oxygen evolution reaction (OER). The 250 mV overpotential (@ 10 mA ⋅ cm−2) and 73.54 mV ⋅ dec−1 Tafel slope required for OER are lower than that of the state‐of‐the‐art Co‐based composites. It has also demonstrated excellent durability in alkaline media indicating its promising potential for practical application in industry. [ABSTRACT FROM AUTHOR]

Technology urges to replace the state-of-the-art catalysts such as platinum with low cost, earth abundant and durable electrocatalysts for efficient hydrogen evolution (HER) reaction which is going to become the major sustainable production of energy in future. Herein, we present the heterostructure based MoS 2.ZnO (MZO) heterostructures for successful electrochemical water splitting process. For HER, the prepared MoS 2.ZnO nanocomposites show the over potential as low as 239 mV at cathodic current density 10 mAcm−2 with an exchange current density of 3.2 μAcm−2. A Tafel slope of about 62 mV per decade suggested to have the Volmer-Heyrovsky mechanism for the HER process with MoS 2.ZnO nanocomposite as the catalyst. The small Tafel slope indicates a promising electrocatalyst for HER in practical application. The strong interface formation at the MoS 2.ZnO heterostructure facilitates higher catalytic activity and excellent cycling stability. The heterostructure formation based on semiconductor two dimensional (2D) transition metal dichalcogenides (TMDC) open up new avenues for effective manipulation of HER catalysts. Image 1 • Green, low cost and reproducible synthesis rout. • Less complicated and large area synthesis without much precaution. • Extendable to other 2D families and metal oxides combinations. • Shows an excellent electrochemical behavior and stability. [ABSTRACT FROM AUTHOR]

• PV-wind hybrid system for sustainable hydrogen production. • Lab-made 3D printed honeycomb shaped cathode substrates. • The enhanced HER performance with Ni, Cu, and NiCu electrodeposition. In this study, a PV-wind hybrid system was proposed as a power source for hydrogen production by alkaline electrolysis and it was examined MATLAB simulation for Adana region. In the alkaline electrolysis cell, lab-made 3D printed cathode substrates were used and its electrocatalytic activity was enhanced via electrodeposition of Ni, Cu and NiCu. The characterization was achieved via scanning electron microscopy, energy-dispersive X-ray, transmission electron microscopy, contact angle measurement and X-Ray diffraction analysis. The electrochemical performance was determined via linear sweep voltammetry, cyclic voltammetry, Tafel polarization measurements, electrochemical impedance spectroscopy, chronoamperometry. Results showed that 3DNiCu electrode exhibited nodular shaped homogeneous surface characteristics and NiCu (1 1 1) and (2 0 0) crystalline morphology; it also demonstrated lower polarization resistance and higher current density during alkaline electrolysis procedure. [ABSTRACT FROM AUTHOR]

Close correlations between (pyrrolic N + Co-N)/(pyridinic N + graphitic N) ratio, work function, d-band center, and η 1000 value highlight CoP@N-glC-3′s optimal performance. [Display omitted] • Ginkgo leaves, in a simple carbothermal reduction, yield efficient carbon-supported CoP electrocatalysts, showcasing a sustainable and straightforward synthesis approach. • Exogenous heteroatoms enhance ampere-level HER by tuning d-band center in CoP electrocatalysts from biomass, promising improved catalytic efficiency. • Close correlations between (pyrrolic N + Co-N)/(pyridinic N + graphitic N) ratio, work function, d-band center, and η 1000 value highlight CoP@N-glC-3′s optimal performance. The incorporation of exogenous heteroatoms presents a promising avenue for enhancing the ampere-level hydrogen evolution reaction (HER) by modulating the d-band center of carbon-supported CoP electrocatalysts derived from biomass. In this study, we synthesized carbon-supported CoP electrocatalysts through a simple carbothermal reduction method, using ginkgo leaves as the carbon source. The composition of nitrogen (N) species in the carbon supports was finely tuned by adjusting melamine (MA) addition, optimizing the valence band structure of resulting CoP@N-glC-m (m = 1, 2, 3, 4, and 5) catalysts through electronic metal-support interactions (EMSIs) with CoP nanoparticles (NPs). By correlating the d-band center, work function, N species contents, and η 1000 value, we observed a close correlation between the variation of the (pyrrolic N + Co-N)/(pyridinic N + graphitic N) ratio, work function, d-band center, and η 1000 value. Notably, CoP@N-glC-3, with the highest ratio of (pyrrolic N + Co-N)/(pyridinic N + graphitic N), exhibited an optimal work function and d-band center, striking a balance between Volmer and Heyrovsky processes, resulting in the highest HER activity among the catalysts. CoP@N-glC-3 demonstrated a 844 mV overpotential, driving the current density to 1000 mA cm−2, more approaching to commercial 20 % Pt/C compared with CoP@glC and CoP@N-glC-m (m = 1, 2, 3 and 5). This research provides crucial insights into electrocatalyst design, connecting chemical properties, valence band structures, and catalytic performance, with profound implications for large-scale HER electrocatalyst production. [ABSTRACT FROM AUTHOR]

Abstract The design of MoS2‐based electrocatalysts with exceptional reactivity and robustness remains a challenge due to thermodynamic instability of active phases and catalytic passiveness of basal planes. This study details a viable in situ reconstruction of zinc–nitrogen coordinated cobalt–molybdenum disulfide from structure directing metal–organic framework (MOF) to constitute specific heteroatomic coordination and surface ligand functionalization. Comprehensive experimental spectroscopic studies and first‐principle calculations reveal that the rationally designed electron‐rich centers warrant efficient charge injection to the inert MoS2 basal planes and augment the electronic structure of the inactive sites. The zinc–nitrogen coordinated cobalt–molybdenum disulfide shows exceptional catalytic activity and stability toward the hydrogen evolution reaction with a low overpotential of 72.6 mV at −10 mA cm−2 and a small Tafel slope of 37.6 mV dec−1. The present study opens up a new opportunity to stimulate catalytic activity of the in‐plane MoS2 basal domains for enhanced electrochemistry and redox reactivity through a “molecular reassembly‐to‐heteroatomic coordination and surface ligand functionalization” based on highly adaptable MOF template.