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Developing new forms of flexible zinc–air (Zn–air) batteries is crucial to economic growth. Nevertheless, the absence of an oxygen evolution reaction catalyst with high catalytic efficiency and low-cost causes instability of Zn–air battery cycling and economic unviability, respectively. In this paper, a leaf-like N-doped carbon structure with CoS2 nanoparticles self-supported on carbon fiber paper (CoS2-CZ@CFP) was developed as an air electrode for Zn–air batteries, which not only uses nonprecious metal elements, but also has a self-supporting configuration, enhancing the contact between the catalyst and electrode while facilitating the transfer of electrons. Sulfur as the source gas was introduced into Co-doped metal–organic skeletons (Co-ZIFs) anchored on carbon fiber paper (CFP) for in situ vulcanizing transition metal Co, which successfully ensures the uniform distribution of sulfide particles in the carbon matrix, hence enriching active catalyst sites. The CoS2-CZ@CFP demonstrated an overpotential of 1.611 V at J = 50 mA cm−2, superior to RuO2@CFP (1.814 V). A Zn–air battery fabricated using the synthesized CoS2-CZ@CFP exhibited an extended life cycle of 117 h. This research paves the way for a novel method of designing self-supporting configurations of sulfides and carbon matrix composites as promising air electrodes applicable to Zn–air batteries. [ABSTRACT FROM AUTHOR]

It is significant to develop low-cost and highly efficient electrocatalysts for the hydrogen evolution reaction (HER) via electrochemical water splitting. Herein, we constructed P-doped NiCo2S4 nanowire arrays on carbon fiber paper (NiCo2S4−xPx/CFP) as a HER electrocatalyst in both acidic and alkaline media. Benefitting from P doping into NiCo2S4, the as-prepared NiCo2S4−xPx/CFP exhibits low HER overpotentials of 80 and 132 mV in acidic and alkaline media at a cathodic current density of 10 mA cm−2, respectively, which are far superior to counterparts of NiCo2S4 nanowire arrays on the carbon fiber paper (NiCo2S4/CFP). Meanwhile, the NiCo2S4−xPx/CFP presents excellent HER stability of 20 hours in acidic and alkaline media. From the results of density functional theory calculations, P doping can not only optimize the hydrogen adsorption energetics on each kind of atomic site of catalysts, but also strengthen the H2O molecule binding ability on the catalyst surface for the alkaline HER and favor kinetics of hydrogen adsorption and H2 formation on the catalyst surface for the acidic HER, eventually improving overall HER performances. The investigation of the HER mechanism modulated by P doping in our work offers novel inspiration to develop highly efficient ternary metal sulfides for the HER. [ABSTRACT FROM AUTHOR]

As one of the effective methods for hydrogen production, water electrolysis has been widely studied. However, the high overpotential challenge faced by the anode and the limitation of the electron transfer rate in this process significantly inhibit the efficiency of hydrogen production, which has become the main obstacle to overcome in the current research. The use of thermodynamically more favorable organic compounds to oxidize at the anode instead of traditional water oxidation (OER) is an effective strategy to optimize the process of electrolytic hydrogen production. In this paper, Ni3S2 catalysts co-doped with non-noble metals Li and Mn were prepared on nickel foam and used for the glycerol oxidation reaction (GOR) coupled with the hydrogen evolution reaction (HER). In alkaline solution, Li, Mn–Ni3S2@NF exhibits good GOR and HER performance. Specifically, overpotentials of 1.58 V vs. RHE and 0.54 V vs. RHE are required to reach a current density of 200 mA cm−2, respectively, and the catalytic performance of the material remains good after a long-term test. Li, Mn–Ni3S2@NF as a bifunctional catalytic material oxidizes glycerol to formate, and its faradaic efficiency (FE) is as high as 91%, and the volume of hydrogen production is close to the theoretical value. In addition, the replacement of the OER by the GOR can reduce the energy consumption by about 17.44%. [ABSTRACT FROM AUTHOR]

The New Journal of Chemistry is a publication that features articles and papers on various topics in chemistry. The current issue includes papers on lithium-sulfur batteries, graphene, and carbon nanotubes, among others. The journal is published by The Royal Society of Chemistry and the Centre National de la Recherche Scientifique. The papers provide valuable insights and findings in their respective fields of research, covering topics such as compound synthesis, crystal structures, magnetic behavior, and the development of new materials for applications like photocatalysis and electrocatalysis. The journal also offers professional recognition and development opportunities for scientists. [Extracted from the article]

The New Journal of Chemistry, published by the Royal Society of Chemistry, features articles on a wide range of topics in chemistry. The current issue covers subjects such as nanosized metals, liquid catalyzed growth of graphene, and photocatalytic CO2 reduction. The journal aims to provide innovative and cutting-edge reports that have a strong chemical component and broad appeal. This document is a compilation of research papers from the journal, covering topics such as electrocatalysts, nanocomposites, halogenation reactions, supramolecular assembly, and more. The papers explore various applications, including agriculture and waste digestion. [Extracted from the article]

Bimetallic two-dimensional (2D) metal–organic framework (MOF) materials display excellent electrocatalytic performance due to the synergistic effect between metals and the advantage of the 2D structure. In this work, Cu was introduced into the 2D Co-MOF structure, and a 2D book-like CuCo-MOF structure was fixed on carbon fiber paper (CFP) for direct electrochemical glucose detection and oxygen evolution reaction (OER). The materials showed good electrocatalytic glucose detection performance with a sensitivity as high as 6.861 mA mM−1 cm−2 and a detection limit as low as 0.12 μM. For the OER, when the current density is 10 mA cm−2, the overpotential (η) is 340 mV, and good stability is maintained for about 10 h without current attenuation. This work not only exploits a new 2D MOF structure containing Cu, but also expands the potential of Cu-containing MOF materials in the electrocatalytic OER, making a contribution to the field of energy conversion and biomolecular sensing. [ABSTRACT FROM AUTHOR]

Developing high-efficiency electrocatalysts for the hydrogen evolution reaction (HER) is of great importance. In this paper, dendrite-free Ni–Cu catalysts were synthesised via one-step pulse electrodeposition under a weak magnetic field (0.5 T). Regardless of the direction of the magnetic field, the ions were affected by the magnetohydrodynamic (MHD) effect, which greatly promoted the mass transfer and dispersion uniformity, and suppressed the uncontrollable agglomeration by electrodeposition. It was found that the nucleation mechanism changed from progressive nucleation under a 0 T magnetic field to instantaneous nucleation under a 0.5 T magnetic field. Large-scale (325 nm, 0 T) dendrite growth on the single-sided plane was successfully suppressed, and replaced by smaller (90 nm, 0.5 T) and uniformly distributed cluster growth around the carbon paper. In addition, the (111) plane was strengthened by the magnetic field. Electrochemical analysis showed that the Ni–Cu catalysts exposed more surface area and exhibited greatly enhanced catalytic activity, which only needed −57.3 mV to deliver the current density of 10 mA cm−2 with a small Tafel slope of 99.4 mV dec−1 in 1 M KOH. Overall, magneto-electrodeposition, especially under weak magnetic field conditions, provides great promise for the preparation of HER catalysts. [ABSTRACT FROM AUTHOR]

In this paper, a novel Pt/CoP/C photo-electro synergistic catalyst was successfully synthesized by a hydrothermal method combined with phosphorus doping treatment. The addition of Vulcan XC-72R is in favor of effectively preventing agglomeration of active catalytic sites, resulting in more uniform and smaller Pt and CoP nanoparticles. The as-obtained Pt/CoP/C shows excellent photo-electro catalytic performance for the HER with simulated solar light irradiation. The optimal hydrogen production is 5384.18 mmol h−1 g−1, which is obviously higher than that of the commercial catalyst (20 wt% Pt/C: 4608.52 mmol h−1 g−1). The research results show that introducing cobalt phosphide into the Pt catalyst can improve the electrocatalytic activity and stability for the HER; in particular, the existence of Co3O4 in Pt/CoP/C leads to an efficient photo-electro catalysis under irradiation, which significantly improves the catalytic activity of Pt. The results above provide a novel strategy for the rational design of cost-effective Pt-based composites towards a fast HER. [ABSTRACT FROM AUTHOR]

Rational design and controllable synthesis of transition metal multi-anionic structures to cooperatively catalyze the hydrogen evolution reaction (HER) and the oxygen evolution reaction (OER) remain a great challenge due to the requirements of high current density and long-term durability for water splitting. Herein, a self-supported sheet-on-sheet hierarchical interface was synthesized via a facile corrosion engineering strategy, where the Ni3S2 microsheet arrays were pre-grown on nickel foam and they provided abundant surface active sites to grow FeOOH nanosheets vertically. The obtained FeOOH/Ni3S2 heterostructure exhibited well-defined dimensions and intimate interface contact with oxygen and a sulfur anion structure, which can modulate the electronic structure of interfacial active sites. Hence, the optimized FeOOH/Ni3S2 required overpotentials of 345 mV and 269 mV to achieve a current density of 100 mA cm−2 for the HER and the OER, respectively. Moreover, it required a voltage of 1.855 V to achieve overall water splitting at a current density of 100 mA cm−2. The interfacial electronic interaction and multi-anionic hierarchical structure not only facilitate the electron transfer between the FeOOH/Ni3S2 surface and intermediate species but also accelerate the kinetic rate. This paper provides a new avenue to design multi-anionic hierarchical structures as cost-effective and highly stable electrocatalysts for practical overall water splitting. [ABSTRACT FROM AUTHOR]

The development of noble-metal-free electrocatalysts with high catalytic efficiency, low cost, and high durability in pH-universal media is encountering a bottleneck in practical applications. In this paper, Ni@MoN-700 coral hybrids were prepared using hydrogen evolution reaction (HER) catalysts, which were synthesized by a high-temperature reduction of NiMoO4 nanorods with urea. It was found that the annealing temperature seriously affects the surface morphology and chemical composition of the catalysts. Besides, structural reorganization occurred during the HER, which involved the joining of pyrrolic N, metal nitrogen, Mo3+, and Mo6+, governing the HER performance. Also, during the HER, Ni and Mo could synergistically improve the overall catalytic activity of the catalysts, via electronic interactions. These advantages endow Ni@MoN-700 with exceptional endurance and great HER activity, with a low overpotential of 30 mV and 76 mV at 10 mA cm−2 in alkaline and acidic media. These characteristics are similar to those of Pt under alkaline conditions. NiMoN catalysts show unusual activity and long-term stability, indicating a wide range of potential applications. [ABSTRACT FROM AUTHOR]

Designing a robust bifunctional water splitting catalyst at low cost is of great importance for water splitting. Herein, the in situ-generated MoS2/NiS2 nanosheet heterostructures by cobalt incorporation on carbon paper (Co–MoS2/NiS2/CP) are first obtained by applying a scalable chemical vapor vulcanization approach. Based on the synergistic effects of cobalt element doping and the construction of MoS2/NiS2 heterostructures, the much enhanced electrocatalytic performance for full water electrolysis is clearly revealed. In particular, the electronic structure of MoS2/NiS2 heterostructures was further effectively modified by cobalt incorporation along with the electron density of catalytic sites, which both promote the Volmer step to speed up alkaline hydrogen evolution reaction (HER) and optimize the oxygen-containing intermediate adsorption to enhance oxygen evolution reaction (OER). Consequently, Co–MoS2/NiS2/CP heterostructures presented low overpotentials (HER: η10 = 109 mV; OER: η10 = 323 mV) in the basic solution. Furthermore, Co–MoS2/NiS2/CP was designed as a two-electrode alkaline electrolytic configuration for full water electrolysis. This strategy experimentally illustrates the feasibility of designing a conventional electrocatalyst for water electrolysis via the cooperative effects of metal doping and heterostructured engineering. [ABSTRACT FROM AUTHOR]

In this paper, NiCo2S4 was coated on the surface of WS2 of a 1T/2H mixed phase by a two-step hydrothermal method to form an in situ core–shell structure. The unique S-scheme heterojunction of the NiCo2S4@WS2 core–shell composite photocatalyst improved the easy recombination of carriers caused by the narrow band gap of NiCo2S4 and WS2, and improved the photocatalytic hydrogen production performance. The loading ratio of NiCo2S4@WS2, the addition of Eosin Y, and the pH value of TEOA were optimized. Under the optimal conditions, the hydrogen production rate reached 5.814 mmol g−1 h−1, which is about 8.55 times and 3.35 times the hydrogen evolution rates of NiCo2S4 and WS2, respectively. The composite catalyst exhibits excellent charge separation efficiency in photoelectrochemistry, PL and BET tests, carrier transport rate and large specific surface area that can provide more active sites, which are the main factors for the improvement of the hydrogen evolution performance. This paper demonstrates new design strategies to drive efficient photocatalytic hydrogen production by building in situ core–shell structures and optimizing the carrier transport paths, which will yield new insights. [ABSTRACT FROM AUTHOR]

In this paper, the structural characteristics and catalytic mechanism for hydrogen evolution of ammonia borane of non-metal (N, S) doped CoP catalysts were studied in detail by density functional theory (DFT) calculations. Specifically, we first investigated the structure of the cobalt phosphide catalyzed ammonia borane models. In addition, based on the most stable structures, the mechanism of the hydrogen evolution reaction of ammonia borane catalyzed by three catalysts was studied, and four feasible reaction paths for the hydrogen evolution reaction of ammonia borane catalyzed by three catalysts were discussed. By comparing the activation energies of the control steps of different reaction paths, the optimal reaction paths for the hydrogen evolution of ammonia borane catalyzed by three different catalysts were determined. The catalytic activities of the three catalysts for the hydrogen evolution of ammonia borane were compared. We found that the N-doped catalyst was beneficial to improve the catalytic activity of CoP for the catalytic hydrogen evolution of ammonia borane, while the catalytic activity of S-doped CoP for the catalytic hydrogen evolution of ammonia borane is relatively weak. These results reveal the relationship between the physical properties of CoP (and its non-metal-doped variants) and their catalytic activity. Finally, these findings can be used to explain the underlying mechanism reported in previous experimental studies from a microscopic perspective. [ABSTRACT FROM AUTHOR]

Cocatalysts are usually applied in the photocatalytic water splitting process to accelerate the kinetics of the hydrogen evolution reaction (HER). Specifically, the transition metal nitride (Mo2N) featuring a unique local surface plasmon resonance (LSPR) effect has exhibited great potential to function as a HER cocatalyst. However, the low metallicity of Mo2N hampers its ability to improve charge separation. To address this issue, transition metal atom doping (Co and Cu) engineering was used to modulate the electronic structure of Mo2N nanosheets to achieve a higher electrical conductivity and a lower hydrogen adsorption free energy (‖ΔGH*‖), thereby favoring the HER kinetics. Density functional theory (DFT) calculations and experimental results showed that Co-doping and Cu-doping mainly take place at Mo sites in the crystal structure of Mo2N to form stable structures of Co doped Mo2N (Co–Mo2N) and Cu doped Mo2N (Cu–Mo2N). Compared with pristine Mo2N, both Cu–Mo2N and Co–Mo2N demonstrated a much improved cocatalytic effect over g-C3N4 in promoting charge separation, accelerating HER kinetics and enhancing light absorption. The Co–Mo2N with the highest conductivity and lowest ‖ΔGH*‖ illustrated the best cocatalytic effect, and the H2 production performance (367.8 μmol g−1 h−1) of Co–Mo2N/g-C3N4 achieved was 10 and 5 times higher than those of Mo2N/g-C3N4 and Cu–Mo2N/g-C3N4. This paper provides significant guidance in the design and development of efficient cocatalysts for the HER application. [ABSTRACT FROM AUTHOR]

Increasing fossil fuel demands and growing concerns of global climate change have stimulated interest in the development of electrocatalysts to produce H2 as an alternative zero-emission fuel from the electrolysis of water via hydrogen evolution reaction (HER). Precious or non-precious catalysts are typically loaded on high surface area carbon materials, and these supports play a critical role in both thermodynamics and kinetics of the HER. In this paper, we evaluate the electrocatalytic activity of a molecular hydrogen evolving catalyst, diacetyl-bis(4-methyl)-3-thiosemicarbazone Ni(II) (Ni-ATSM), on three different carbon surfaces: glassy carbon, carbon paste and pencil graphite. The overpotential for each modified electrode was benchmarked at a current density of −10 mA cm−2. Carbon paste electrodes showed highest overpotentials (495 mV) compared to the other electrode surfaces. Polished pencil and glassy carbon modified electrodes performed similarly (η = 395 mV for GCE and η = 400 mV for pencil). Pencil electrodes etched in acetone overnight prior to Ni-ATSM deposition produced lowest overpotentials (η = 354 mV). Etching results in an increase in electroactive surface area and substantial decrease in the charge transfer resistance of the graphitic interface from 275 Ω to 50 Ω, verified using electrochemical impedance spectroscopy (EIS). Our studies demonstrate pencil graphite may serve as versatile, disposable, cost effective, and reproducible electrode surface for the evaluation of heterogeneous HER catalysts. Moreover, pencils can be easily cut with table saw to generate new surface for easy characterization of the surface such as electrochemistry, imaging and spectroscopy. [ABSTRACT FROM AUTHOR]

FeCo2O4 is a potential OER catalyst, but its catalytic activity still needs to be further improved due to its poor electrical conductivity and low material utilization. In this paper, we construct oxygen-vacancy-rich two dimensional FeCo2O4 nanosheet materials using a liquid-phase reduction strategy. Benefiting from its large specific surface area, numerous surface catalytic sites, enhanced electrical conductivity, and modulated electronic structure, the catalyst exhibits an overpotential of only 270 mV at a current density of 10 mA cm−2, which is lower than that of the original FeCo2O4 nanosheets (420 mV). At the same time, the catalyst can run steadily for 20 hours without obvious decay. [ABSTRACT FROM AUTHOR]

Transition metal nitrides have good metallic conductivity and high pseudocapacitance, which have drawn extensive attention in the research of Zn-ion energy storage systems. In this paper, we present a novel fabrication of carbon cloth-supported TiN-coated carbon nanotube composites (TiN/CNTs@CC and TWC) via a CVD–ALD method using ethanol, TiCl4 and H2O as precursors. The prepared TWC composites can be used as self-supported electrodes with good flexibility and conductivity. Electrochemical performance tests show that the TiN/CNTs@CC electrode has a high specific capacitance of 363.5 F g−1 at 0.5 A g−1, good rate capability and excellent cycling stability with 92.9% capacity retention over 10 000 charge/discharge cycles. Impressively, the assembled zinc ion hybrid capacitor can achieve a high energy density of up to 81.8 W h kg−1 at a power density of 137.7 W kg−1. Even at a power density of 3013.7 W kg−1, a high energy density of 26.4 W h kg−1 is still achieved. This study provides a new insight into the application of nitride-derived carbon materials in zinc-ion hybrid capacitors. [ABSTRACT FROM AUTHOR]

Water electrolysis is one of the most promising approaches for producing hydrogen. However, the OER, kinetics are sluggish and necessitate highly efficient electrocatalysts to speed up the reaction. In this work, we used NiCo glycerate solid nanospheres as a precursor to construct Fe–Ni–Co trimetallic oxide nanospheres utilizing a solvothermal-annealing and stirring technique. The oxygen evolution reaction (OER) activity of the Fe–Ni–Co spheres was greatly enhanced after Fe doping. Among these samples, the FeNiCo-15 hierarchical yolk–shell spheres needed overpotentials of only 204 and 178 mV for the OER and HER, respectively, to drive a current density of 10 mA cm−2, and showed good electrochemical stability. Further, it also presented superior electrocatalytic activity in terms of full water splitting, which was comparable to the integrated performance of the Pt‖IrO2 couple. A cell voltage of only 1.61 V was required to attain a current density of 10 mA cm−2. This paper provides a promising method for developing efficient bifunctional electrocatalysts driving redox electrocatalysis. [ABSTRACT FROM AUTHOR]

In contrast to irregular polycrystals, the orderly structure and the clear surface atomic termination layer of porous single crystals demonstrate unique physical and chemical properties, including excellent electrical conductivity, an extremely large specific surface area, a small grain boundary area and low interfacial resistance. This could provide sufficient well-defined active sites for improving the catalytic activity and stability. Here, we grow well-shaped porous single-crystalline vanadium nitride octahedra and irregular porous polycrystalline vanadium nitride from non-porous NH4V4O10 single-crystal precursors. These well-shaped porous single-crystalline materials show a superior hydrogen evolution reaction (HER) performance. When used as HER catalysts, the overpotential of the VN porous single crystal is only 74.67 mV at a current density of 10 mA cm−2. By contrast, the overpotential of the irregular VN porous polycrystal is 150.66 mV under the same experimental conditions, which demonstrates the unique nature of the porous single-crystalline octahedron material. In contrast to traditional irregular polycrystals, this paper inspires the construction of porous single-crystalline materials with a crystal structure of long-range order of in the micron range for significantly improving the electrocatalytic performance. [ABSTRACT FROM AUTHOR]

In this paper, we investigate the electro-catalytic hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) of synthesized copper tungsten oxide@reduced graphene oxide (CuWO4@rGO) nanocomposites. The prepared CuWO4@rGO nanocomposites show bifunctional electro-chemical performances for the HER and OER via water splitting reactions in alkaline (0.5 M KOH) and acidic (0.5 M H2SO4) media. Cyclic voltammetry (CV) and linear sweep voltammetry (LSV) reveal superlative HER and OER performances of the CuWO4@rGO nanocomposites. The onset over-potentials of the CuWO4@rGO nanocomposites were found to be ∼270 and ∼330 mV for the OER in 0.5 M KOH and 0.5 M H2SO4, respectively, while the onset potentials were found to be ∼180 and ∼135 mV for the HER in 0.5 M KOH and 0.5 M H2SO4, respectively. The CuWO4@rGO nanocomposites also showed lower Tafel slopes of ∼110 and ∼315 mV dec−1 for the OER in 0.5 M KOH and 0.5 M H2SO4, respectively, while the Tafel slopes of the CuWO4@rGO nanocomposites were found to be ∼192 and ∼212 mV dec−1 for the HER in 0.5 M KOH and 0.5 M H2SO4, respectively. Hence, the small energy loss of low-cost electro-catalysts during electro-chemical water splitting reactions reveals comparable HER/OER performances with noble electro-catalysts. [ABSTRACT FROM AUTHOR]

The development of high-efficiency and low-cost photocatalysts for hydrogen production reactions is very important to solve energy problems. In this paper we study the photocatalytic H2 evolution activity of a CeO2/CoS2 heterojunction catalyst under visible light. Characterization studies such as XRD and XPS proved the successful synthesis of a CeO2/CoS2 catalyst. The composite catalyst with a CeO2 and CoS2 mass ratio of 1 : 20 had the best activity, and the hydrogen evolution rate reached 5172.20 μmol g−1 h−1. BET and UV-Vis DRS characterization showed that the introduction of CeO2 not only increased the specific surface area of the composite catalyst, but also improved the response of the photocatalyst to visible light. In addition, PL and electrochemical experiments showed that the electrons and holes of the CeO2/CoS2 catalyst could be quickly separated and transferred, thereby accelerating the kinetics of the hydrogen evolution reaction. This work provided an experimental basis for designing a composite photocatalyst with high stability and hydrogen production activity. [ABSTRACT FROM AUTHOR]

Highly effective bifunctional oxygen electrocatalysts play a key role in fuel cells (FCs), metal–oxygen batteries, and water splitting devices. In this paper, metal organic layer (MOL) derived Co/Co9S8 nanoparticles coated with N,S co-doped graphene-like carbon nanosheets were synthesized with the help of the space-confinement effect of montmorillonite (MMT). The as-prepared material shows excellent electrocatalytic activity both for oxygen reduction and oxygen evolution reactions in 0.1 M KOH solution: its ORR onset potential is 0.93 V (vs. RHE) and the limiting diffusion current density is 4.7 mA cm−2. Moreover, the retention of current for the as-prepared material is 85% after a stability test for 10 000 s for the ORR, while those of the template free catalyst and commercial Pt/C glided below 80%. Additionally, its Tafel slope is 265 mV dec−1, which is much smaller than that of the control sample, suggesting the excellent OER kinetics. The excellent catalytic activity and stability can be attributed to the relatively higher specific surface area, higher number of pyridinic-N and Co–Nx active sites, and higher graphitization degree compared to the template free catalyst. [ABSTRACT FROM AUTHOR]

The development of earth-abundant and high-efficiency electrocatalysts for overall water splitting is highly fascinating and still presents a challenge caused by the low activity for both the hydrogen evolution reaction (HER) and the oxygen evolution reaction (OER) at the same time. In this paper, active cobalt-doped pyrite nanospheres with a porous structure are fabricated for the first time as advanced catalysts for water splitting in an alkaline solution. With the incorporation of cobalt atoms, the electronic structure of pyrite is well-tuned, with high conductivity as well as more active sites being obtained, which finally results in a superior bifunctional water splitting performance. Only 1.60 V is required to reach the current density of 10 mA cm−2, which is smaller than that of other transition metal sulfides. [ABSTRACT FROM AUTHOR]

This paper reports the synthesis of bare TiO2 and various molar concentrations of ruthenium (Ru)-doped TiO2 nanoparticles by the precipitation method. The as-synthesized photocatalysts were characterized by X-ray diffraction (XRD), high-resolution transmission electron microscopy (HRTEM), ultraviolet-visible diffuse reflectance spectroscopy (UV-vis DRS), N2 adsorption/desorption techniques, X-ray photoelectron spectroscopy (XPS), energy dispersive spectroscopy (EDS), Raman spectroscopy, photoluminescence spectroscopy (PL), and electrochemical measurements. The results from the UV-vis spectroscopy clearly indicated a red-shift of the optical response toward the visible region owing to the reduced band gap energy, thus showing an enhancement of the absorption in the visible spectrum. The XRD study showed that the samples were crystallized with the photoactive anatase phase of TiO2. The microstructural study using Raman spectroscopy indicated that the Ru dopant occupied the substitutional sites in the TiO2 lattice. According to the Mott–Schottky analysis, the flat band potential of the Ru-doped TiO2 was shifted to the negative potential. The photocurrent, electrochemical impedance spectroscopy, and photoluminescence revealed a higher photogenerated charge-carriers separation efficiency of the doped sample. The photocatalytic activities of the bare TiO2 and (0.05–0.2 mol%) Ru-doped TiO2 nanoparticles were examined by studying the hydrogen production from water using methanol as a sacrificial reagent and Pt nanoparticles as a cocatalyst under light of λ≥ 320. The optimal iron content was determined to be 0.1 mol% and the corresponding hydrogen production rate was 3400 μmol h−1 in aqueous methanol, which is enhanced by more than 2 times compared to bare TiO2 (1500 μmol h−1) under the same reaction conditions. The higher activity for the doped materials was attributed to the presence of the Ru dopant to facilitate the visible-light-driven activity by introducing the electron donor/acceptor level of ruthenium and the mid-band energy level of defects between the conduction band minimum and valence band maximum of TiO2. [ABSTRACT FROM AUTHOR]

Combining photochemical and electrochemical energy conversion into a single catalytic system is an efficient method for energy generation. In this paper, to increase the electrocatalytic activity of 2H-WS2 nanosheets, CdSe quantum dots (QDs) are introduced as sensitizers to design a novel photo-responsive electrode. The electrocatalytic HER activity of the nanocomposites is observably enhanced under 300 W Xe lamp irradiation (λ≥ 420 nm, the overpotential decreases from −1030 mV vs. RHE to −400 mV vs. RHE at a cathodic current density of 10 mA cm−2 in neutral electrolyte without adding any sacrificial agent, and the Tafel slope decreases from 132 mV dec−1 to 56 mV dec−1). Moreover, the photo-enhanced electrocatalyst demonstrates high stability, which is reflected by a steady-state performance for more than 24 h. This strategy may have potential use in designing and fabricating novel photo-assisted electrocatalysts. [ABSTRACT FROM AUTHOR]

As a dual-functional catalyst for the hydrogen evolution reaction (HER) and the oxygen evolution reaction (OER), Ru clusters have great potential, but there are certain difficulties regarding their stability on the substrate and the tunability of their electronic environment. Here, the S doped graphited biochar aerogel electrocatalyst was designed and synthesized using terrestrial lignin and algal polysaccharide as a carbon substrate. The Ru clusters were anchored on the S-doped carbon aerogel (P-Ru/SC) by carefully designing the Ru-S bond via a novel plasma assisted high temperature carbonization treatment. The optimized P-Ru/SC-2 catalyst exhibits excellent electrocatalytic performance for the HER and OER, achieving ultra-small overpotentials of 119.6 mV and 193.4 mV at 10 mA cm-2. The dual-electrode requires only 1.47 V to reach 10 mA cm-2. It is worth noting that a large number of S sites on graphited carbon can strongly interact with the Ru clusters, significantly improving the catalytic activity and stability for the HER and OER. [ABSTRACT FROM AUTHOR]

Cellulose nanofiber (CNF) is an environmentally friendly material with a high specific surface area, which is an ideal candidate for cathode catalysts in zinc–air batteries (ZABs). However, untreated CNF-based carbon materials suffer from low intrinsic activity and fewer micro-mesopores. Herein, we developed an N-doped porous carbon aerogel from CNF and graphite phase carbon nitride (g-C3N4) via hydrothermal pretreatment and the carbonization process. The CNF can serve as the skeleton of the aerogel that leads to an interconnected porous structure, while g-C3N4 guarantees the in situ N doping and the formation of more nanopores. Therefore, the as-prepared carbon aerogel exhibits excellent oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) performances owing to the successful N doping with sufficient graphite-N and pyridine-N active sites (69.1%) and high specific surface areas (785.4 m2 g−1). The assembled ZABs with a carbon aerogel deliver a specific capacity of 790 mA h g−1 and an energy density of 945.6 W h kg−1 with a long-term stability over 100 h. This work opens a new avenue for the effective conversion of abundant biomass into bifunctional air cathodes for energy-related applications. [ABSTRACT FROM AUTHOR]

MoS2 as one graphene-like 2D layered transition metal sulfide has attracted great attention. However, its application for the HER is still restricted by the poor electrical conductivity and structural restacking. In this work, we developed a facile method to prepare MoO2@MoS2 heterostructures in situ by partial conversion of MoOx into MoS2 on carbon cloth. Based on the two-time hydrothermal process, the MoS2 nanosheets can be dispersed and grow on carbon cloth. Excellent electrochemical HER activity of MoO2@MoS2/CC-2 can be achieved with a low overpotential of 115 mV at 10 mA cm−2 (η10) in 0.5 M H2SO4. Furthermore, it still shows durable electrocatalytic stability for 13 h. The outstanding electrocatalytic activity may be ascribed to the synergistic effect between the MoO2 and MoS2 heterostructures. [ABSTRACT FROM AUTHOR]