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Atomic isolated and dispersed single atom catalyst is ideal for high-performance industrial catalyst. However, the contribution from small amounts of nanoclusters coexisting with single atoms to the catalytic reaction activity is often neglected. In this work, a MXene-supported uniformly dispersed Pt single atoms and nanoclusters (Pt 1 +Pt n /MXene) were obtained by self-assembly through an impregnation method. The catalyst exhibits high electrochemical performance in the hydrogen evolution reaction with an overpotential of only 61.3 mV and a Tafel slope of 32.5 mV dec−1 at a current density of 10 mA cm−2 in an acidic environment. The XAFS analysis and further DFT calculation indicate that the synergistic effect between single atoms and nanoclusters can facilitate adsorption of H* and promote the HER reaction. This work provides an efficient method for integrating multiple active sites in noble metal catalysts. • Constructing Pt sites on MXene enables a strong synergism between nanoclusters and single atoms. • Pt 1 +Pt n /MXene possesses large numbers of highly active Ti–O–Pt interfacial sites. • Ti–O–Pt sites make Pt 1 +Pt n /MXene obtain an outstanding catalytic performance in HER. • Pt 1 +Pt n /MXene boosts the adsorption of H* and promotes the HER reaction process. [ABSTRACT FROM AUTHOR]

The advancement of effective and robust catalysts that can replace the precious-metal-based benchmarks for electrocatalytic overall water splitting is a highly fashionable approach to exploring sustainable energy utilization and addressing environmental issues. Herein, we demonstrate a facile single-step fabrication of NiS-NiS 2 nanoparticles in situ grown on the layered porous sulfur-doped graphitic carbon nitride nanosheets (NiS-NiS 2 /SGCN) act as bifunctional electrocatalysts for hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) in an alkaline medium. Further, an increasing the Ni precursor (fixed sulfur source) increases the formation of NiS-NiS 2 on the surface of SGCN (labeled as NS-1.0, NS-2.0, and NS-3.0). Structural and morphological studies such as PXRD, XPS, FTIR, HR-TEM, etc., revealed a uniform distribution of NiS/NiS 2 on the surface of S-g-C 3 N 4 nanosheets. The OER and HER activity of NiS-NiS 2 /SGCN nanohybrid were significantly enhanced by increasing the affinity of accessible surface-active edge sites, interfacial contact allows effective modification of electronic structure, high structural porosity, redox-active centers of Ni2+/Ni3+, and rich in sulfur vacancy. In addition, the enhancement of the exposure of the edge sites is improved by their attachment to a sulfur-doped g-C 3 N 4 framework. As a result, in the half-cell experiments, the NiS-NiS 2 /SGCN (NS-3.0) catalyst exhibited enhanced performance in both OER and HER, requiring an overpotential of 298 mV to reach 50 mA/cm2 for OER and −144 mV to reach 10 mA/cm2 for HER. Furthermore, the constructed electrolyzer using Ni-S 3.0 as the cathode and anode required a cell voltage of 1.66 V to yield 50 mA/cm2 in overall water splitting. This study may inspire the in-situ synthesis of different metal sulfides on SGCN to provide a unique interfacial approach for improving the performance of bifunctional non-precious electrocatalysts. NiS-NiS2/SGCN as Bifunctional Electrocatalysts for HER and OER in an alkaline medium. [Display omitted] • Single-step fabrication of NiS-NiS 2 grown insitu on sulfur-doped graphitic carbon nitride. • NiS-NiS 2 /SGCN/NF exhibited a low OER overpotential of 298 mV (at 50 mA/cm2). • NiS-NiS 2 /SGCN/NF showed a low HER overpotential of −144 mV (at 10 mA/cm2). • NiS-NiS 2 /SGCN/NF electrode acts as a bifunctional electrocatalyst in alkaline media. [ABSTRACT FROM AUTHOR]

The electrolysis of water is the key method for hydrogen production but the high overpotential necessitates electrocatalysts. Traditionally, Pt is used, but it is scarce and costly. Herein, MnCO 3 is unveiled as an electrocatalyst for the production of hydrogen. MnCO 3 is electrodeposited onto pencil graphite by chronoamperometric method and confirmed by XRD and vibrational spectroscopic studies. MnCO 3 electrodeposited for 15 min at 2 V demonstrates a good HER activity (overpotential of 123 mV to reach 10 mA cm−2) in 0.5 M H 2 SO 4 with a Tafel slope of 79 mV dec−1. In addition, MnCO 3 exhibited good stability during continuous operation (over 3000 cycles and 14 h). Though MnCO 3 requires higher overpotential than the benchmark catalyst (Pt/C) to reach 10 mA cm−2, it outperforms Pt/C at higher current density (≥75 mA cm−2) demonstrating that MnCO 3 could be used as an electrocatalyst to produce H 2 at a high rate from acidic medium. [Display omitted] • MnCO 3 is electrodeposited onto pencil graphite by chronoamperometry method. • MnCO 3 electrodeposited at 2 V demonstrates a good HER activity in 0.5 M H 2 SO 4. • MnCO 3 exhibits good stability (over 3000 cycles and 14 h of continuous operation). • MnCO 3 surpassed the performance of Pt/C at 100 and 200 mA cm−2 [ABSTRACT FROM AUTHOR]

The activation of lattice oxygen oxidation mechanism (LOM) will endow iridium‐based electrocatalysts with desired acid‐available water oxidation activity, compared to the conventional adsorbate evolution mechanism (AEM). However, the inherent symmetric [IrO6] octahedra of commercial Ir‐based catalysts generally thermodynamically favor the AEM pathway contributing to the moderate water oxidation performance. Here, based on typical layered Ca2IrO4 (CIO) modeled materials, the d‐orbitals electron repulsion strategy is demonstrated, via constructing asymmetrically polarized Ir‒O‒Ru configuration in Ru‐CIO, to effectively activate the lattice oxygen participating in water oxidation process for decent oxygen‐related electrocatalytic activity. Specifically, a great increase of ≈700‐fold and ≈170‐fold in mass activity and turnover frequency, respectively, has been realized for the optimal Ru‐CIO electrocatalyst in an acid medium relative to the commercial IrO2 electrocatalysts, where a small overpotential of only 175 mV is required for achieving 10 mA cmgeo‒2. In situ X‐ray fine structure spectroscopies combined with in situ 18O‐ isotope‐labeled differential electrochemical mass spectrometry analyses reveal that desirable LOM has been boosted by the activated lattice oxygen and the flexible Ir(3+δ)+ active sites of asymmetric [IrO6] octahedra, which results in superior OER kinetics for Ir‐based oxide catalysts. [ABSTRACT FROM AUTHOR]

The reconstruction of local electronic states in Pt-O x is an effective strategy for balancing charge distribution and enhancing the intrinsic activity of noble metals. This study presents the use of highly porous and oxygen-rich activated bluecoke powders as a desirable carbon support, and regulates Pt-O x bonds by incorporating the Fe as transition metal, leading to the development of an efficient bluecoke-based electrocatalyst characterized (Fe/Pt–O@MKABC) by exceptionally low Pt loading. The loading amount of Pt in Fe/Pt–O@MKABC is only 0.98 wt%, which is less than the 5% reported for commercial Pt/C catalyst, yet its hydrogen evolution performance is comparable. The developed catalyst presents exciting catalytic ability with overpotential of only 17 mV at 10 mA/cm2, a high mass activity of 8.3 A/(cm2·mg pt) at 50 mV, a large turnover frequency of 8.29 H 2 /s, and outstanding durability with a mere increase of 5 mV over 10000 cycles in acidic electrolyte. Detailed spectroscopic analysis and theoretical calculation results demonstrate that the abundant oxygen on activated bluecoke powders provides an opportunity for the construction of Fe-O y and Pt-O x. The introduction of Fe leads to electron rearrangement in Fe/Pt–O@MKABC, promoting electron transfer and reducing the adsorption free energy of H*, and the interaction between Fe-O y and Pt-O x enhances the hydrogen evolution reaction (HER) performance. [Display omitted] • Utilizing highly porous and oxygen-rich activated bluecoke powders as defect carbon support. • The introduction of Fe optimizes the Pt-O x bonds and significantly reduces the Pt loading. • The loading amount of Pt in the developed Fe/Pt–O@MKABC electrocatalyst is only 0.98 wt%. • The interaction between Fe-O y and Pt-O x accelerates the Volmer-Heyrovsky process. [ABSTRACT FROM AUTHOR]

The electrocatalytic performance of a Fe65Co10Si12.5B12.5 Fe-based compounds toward alkaline hydrogen evolution reaction (HER) is enhanced by dealloying. The dealloying process produced a large number of nanosheets on the surface of NS-Fe65Co10Si12.5B12.5, which greatly increased the specific surface area of the electrode. When the dealloying time is 3 h, the overpotential of NS-Fe65Co10Si12.5B12.5 is only 175.1 mV at 1.0 M KOH and 10 mA cm−2, while under the same conditions, the overpotential of Fe65Co10Si12.5B12.5 is 215 mV, which is reduced. In addition, dealloying treated electrodes also show better HER performance than un-dealloying treated electrodes. With the increase in Co doping amount, the overpotential of the hydrogen evolution reaction decreases, and the hydrogen evolution activity is the best when the addition amount of Co is 10%. This work not only provides a basic understanding of the relationship between surface activity and the dealloying of HER catalysts, but also paves a new way for doping transition metal elements in Fe-based electrocatalysts working in alkaline media. [ABSTRACT FROM AUTHOR]

In this paper, macroporous high‐entropy spinel oxide (HESO) (Fe0.2Ni0.2Co0.2Mn0.2Zn0.2)3O4 monoliths were successfully fabricated via a sol–gel method followed by calcination. Appropriate polyacrylic acid and propylene oxide contents allow the formation of three‐dimensional co‐continuous xerogel monoliths, and the water/glycerol ratio controls the macropore size of monoliths. Subsequent calcination achieves the precipitation of HESO (Fe0.2Ni0.2Co0.2Mn0.2Zn0.2)3O4 with a singular phase and exceptional structural stability. The macroporous HESO (Fe0.2Ni0.2Co0.2Mn0.2Zn0.2)3O4 demonstrates remarkable performance in the oxygen evolution reaction (OER) with an overpotential of 333 mV at 100 mA cm−2 and a Tafel slope of 43.2 mV dec–1, surpassing that of RuO2 (391 mV) under identical conditions. Furthermore, the catalytic stability of the HESO catalyst remains superior even after 24 h of testing. This process offers a promising avenue for the development of macroporous high‐entropy oxide OER catalysts for overall water splitting. [ABSTRACT FROM AUTHOR]

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

Long‐term operation of proton exchange membrane water electrolysis (PEMWE) poses significant challenges due to the high potential and strong acidic environment associated with the oxygen evolution reaction (OER), leading to severe catalyst degradation. Here, ultrafine iridium–ruthenium nanowires (IrRu NWs) are developed through a facile process, which exhibits excellent activity and stability for acidic OER. The IrRu NWs achieve an overpotential of 243 mV at 10 mA cm−2, which is significantly lower than that of commercial IrO2 and pure Ir nanowires. Importantly, the IrRu NWs demonstrate 17.6% higher current density at 2 V in real PEMWE device than that of the commercial IrO2 and Pt/C catalysts at the anode and cathode, respectively. The PEMWE device with the IrRu NWs catalyst layers can be stably operated at 1.0 and 1.5 A cm−2 for more than 500 h with a degradation rate of only 28 µV h−1, which makes the IrRu NWs a promising catalyst toward PEMWE applications. [ABSTRACT FROM AUTHOR]

Over the last decades, the transition metal dichalcogenide (TMD) materials have been intensively investigated for hydrogen evolution reaction (HER). Among many TMD catalysts, MoS2 and WS2 are the most efficient materials for HER application because of their advantages including earth abundance, facile synthesis, and high catalytic activities. Herein, a simple and scalable process is introduced which was employed to prepare the nanoflower (NF) heterostructure of MoS2 and WS2 (MoS2/WS2 NF). The superior catalytic activity of the synthesized MoS2/WS2 NF could be contributed by the unique properties of the heterostructure between WS2 and MoS2 materials. Low overpotential (251 mV) at a current density of 10 mA cm−2, small Tafel slope (61 mV dec−1), good conductivity, and superstability are the main properties of the prepared MoS2/WS2 NF. This work presents a new facile novel to prepare efficient catalysts which could be great candidates for HER and electrocatalytic application. [ABSTRACT FROM AUTHOR]

Hydrogen production from seawater remains challenging due to the deactivation of the hydrogen evolution reaction (HER) electrode under high current density. To overcome the activity-stability trade-offs in transition-metal sulfides, we propose a strategy to engineer sulfur migration by constructing a nickel-cobalt sulfides heterostructure with nitrogen-doped carbon shell encapsulation (CN@NiCoS) electrocatalyst. State-of-the-art ex situ/in situ characterizations and density functional theory calculations reveal the restructuring of the CN@NiCoS interface, clearly identifying dynamic sulfur migration. The NiCoS heterostructure stimulates sulfur migration by creating sulfur vacancies at the Ni3S2-Co9S8 heterointerface, while the migrated sulfur atoms are subsequently captured by the CN shell via strong C-S bond, preventing sulfide dissolution into alkaline electrolyte. Remarkably, the dynamically formed sulfur-doped CN shell and sulfur vacancies pairing sites significantly enhances HER activity by altering the d-band center near Fermi level, resulting in a low overpotential of 4.6 and 8 mV at 10 mA cm−2 in alkaline freshwater and seawater media, and long-term stability up to 1000 h. This work thus provides a guidance for the design of high-performance HER electrocatalyst by engineering interfacial atomic migration. Stable and efficient hydrogen production from seawater remains challenging. Here the authors engineer sulfur migration in NiCoS electrocatalyst via N-doped carbon encapsulation, generating S vacancies and S doped CN active sites at the interface that improves electrocatalytic hydrogen evolution activity and durability in both alkaline freshwater and seawater. [ABSTRACT FROM AUTHOR]

Electrochemical water splitting is an ideal alternative to obtain hydrogen, which is a renewable and clean source of energy with a high calorific value. Designing a highly stable and affordable catalyst is a critical need for achieving the desired electrocatalytic efficacy. Three-dimensional (3D) nanomaterials (NMs) have a hierarchical or interconnected network or framework-like structure with commendable mechanical stability. They possess large surface area and electroactive sites, which have garnered immense scientific interest in the past few years. Different 3D NMs that have been used for electrocatalysis of water are the central focus of this review. There are only a handful of reports discussing them in the literature, but none of them comprehensively cover various 3D NMs as water-splitting catalysts. In addition, the basic concepts of hydrogen evolution reaction (HER) and oxygen evolution reaction (OER), as well as various metrics affecting water splitting kinetics, have been highlighted in detail. In the end, hurdles in the design and commercialization of highly stable water-splitting catalysts and their possible remedies have been discussed along with. [Display omitted] • Electrochemical water splitting is a plausible approach for producing hydrogen. • 3D nanostructured electrocatalysts have enhanced the efficacy of water splitting. • Fabrication and electrocatalytic activity of 3D nanocatalysts have been focussed. • Various metrics affecting the water splitting kinetics have also been discussed. • Hurdles in design and commercialization of these catalysts have been highlighted. [ABSTRACT FROM AUTHOR]

The design of high‐entropy single‐atom catalysts (HESAC) with 5.2 times higher entropy compared to single‐atom catalysts (SAC) is proposed, by using four different metals (FeCoNiRu‐HESAC) for oxygen reduction reaction (ORR). Fe active sites with intermetallic distances of 6.1 Å exhibit a low ORR overpotential of 0.44 V, which originates from weakening the adsorption of OH intermediates. Based on density functional theory (DFT) findings, the FeCoNiRu‐HESAC with a nitrogen‐doped sample were synthesized. The atomic structures are confirmed with X‐ray photoelectron spectroscopy (XPS), X‐ray absorption (XAS), and scanning transmission electron microscopy (STEM). The predicted high catalytic activity is experimentally verified, finding that FeCoNiRu‐HESAC has overpotentials of 0.41 and 0.37 V with Tafel slopes of 101 and 210 mVdec−1 at the current density of 1 mA cm−2 and the kinetic current densities of 8.2 and 5.3 mA cm−2, respectively, in acidic and alkaline electrolytes. These results are comparable with Pt/C. The FeCoNiRu‐HESAC is used for Zinc–air battery applications with an open circuit potential of 1.39 V and power density of 0.16 W cm−2. Therefore, a strategy guided by DFT is provided for the rational design of HESAC which can be replaced with high‐cost Pt catalysts toward ORR and beyond. [ABSTRACT FROM AUTHOR]

In this work, we demonstrate an interface on porous nickel foam (NN) between crystalline nickel sulfide and amorphous nickel sulfide (NNS/NNSx) adapting simple hydrothermal and facile electrodeposition processes, respectively. The developed electrocatalyst required a low overpotential of 15 mV to deliver a current density of 10 mA cm−2 and the interface intrinsically activates the electrocatalyst with an onset overpotential comparable to that of Pt in an alkaline hydrogen evolution reaction. [ABSTRACT FROM AUTHOR]

Designing electrocatalysts for electrochemical water splitting to generate renewable energy has been a prospective interest throughout the previous decade. The efficiency of electrochemical water splitting, however, is impeded by the sluggish kinetics of the oxygen evolution reaction (OER). Herein, the heterostructure of layered double hydroxides (NiFe-LDH) and MXene (Ti 3 C 2 T x) were synthesized via hydrothermal (NiFe-LDH/Ti 3 C 2 T x -H) and physical mixing (NiFe-LDH/Ti 3 C 2 T x -P) methods. The NiFe-LDH/Ti 3 C 2 T x -H exhibited an overpotential of 269 mV at 10 mA cm−2, indicating superior performance as compared to NiFe-LDH/Ti 3 C 2 T x -P (353 mV) and RuO 2 (313 mV). The double layer capacitance (C dl) of NiFe-LDH/Ti 3 C 2 T x -H was higher (2.05 mF cm−2) as compared to NiFe-LDH/Ti 3 C 2 T x -P (1.63 mF cm−2), thus indicating more active sites for improving reaction kinetics. Additionally, the NiFe-LDH/Ti 3 C 2 T x -H electrocatalyst retained stable performance (96.1%) after 10 h of chronopotentiometry at a constant current density of 10 mA cm−2. [Display omitted] • Synthesized novel NiFe-LDH/Ti 3 C 2 T x -H heterostructure via hydrothermal route. • Uniform growth of NiFe-LDH prevents the agglomeration of NiFe-LDH and Ti 3 C 2 T x. • The strong interfacial interactions enhance the catalytic efficiency. • NiFe-LDH/Ti 3 C 2 T x -H exhibited a lower overpotential of 269 mV at 10 mA cm−2 for OER. [ABSTRACT FROM AUTHOR]

The investigation delves into the functionality exhibited by ferroelectric BiFe0.95Mn0.05O3 (BFM) nanoparticles (NPs) concerning the hydrogen evolution reaction (HER). The electrocatalytic activity of BFM NPs undergoes a transformative shift as a consequence of mono‐, di‐, and tri‐valent cation substitution. Notably, the strategic engineering of doping at the Bi site within BFM NPs yields a remarkable outcome, namely the conspicuous reduction of the kinetic overpotential prerequisite for HER. This diminished overpotential in doped BFM NPs arises from the confluence of multifarious factors: diminished charge transfer resistance, augmented specific surface area, a discernible distribution of pore sizes ranging from narrow to broad, particles endowed with a shape boasting abundant active facets, and the integration of dopants as novel active sites on the surface. Furthermore, the presence of surface defects, oxygen vacancies, and amplified microstrain within doped BFM NPs contributes to the reduction in overpotential. [ABSTRACT FROM AUTHOR]

Self-supported Ru-doped NiMoO4 (Ru–NiMoO4) is synthesized on commercial NiMo foam. The Ru–NiMoO4 exhibits extremely high performance for electrocatalytic hydrogen evolution with a small overpotential of 170.6 mV to afford a current density of 1000 mA cm−2, and excellent durability for 150 hours in alkaline solution. [ABSTRACT FROM AUTHOR]

In the realm of sustainable and environmentally friendly "green-hydrogen" fuel demand, water electrolysis stands as a pathway of hope for the extraction of renewable hydrogen. However, the durability and efficiency of electrocatalysts have been a major challenge in this process, owing to factors like the high costs of noble catalysts (Pt, Ir, Ru, etc.) and their limited stability. Layered Nickel-iron double hydroxides (NiFe-LDH) have shown potential as low-cost and efficient electrocatalysts because of their suitable electronic configuration and distinguished orbital confinement. However, their durability In the realm of sustainable and environmentally friendly "green-hydrogen" fuel demand, water electrolysis stands as a pathway of hope for the extraction of renewable hydrogen. However, the durability and efficiency of electrocatalysts have been a major challenge in this process, owing to factors like the high costs of noble catalysts (Pt, Ir, Ru, etc.) and their limited stability. Layered Nickel-iron double hydroxides (NiFe-LDH) have shown potential as low-cost and efficient electrocatalysts because of their suitable electronic configuration and distinguished orbital confinement. However, their performance and durability in corrosive alkaline water at high current density remain limited. In this regard, one can make the nano-composites of this NiFe-LDH with high electronic conductivity materials and layered structures like VSe 2. With this motivation, this work presents a novel electrocatalyst, NiFe-LDH, supported with VSe 2 nanosheets ( V Se 2 / NiFe − LDH), designed to address these challenges and enhance water splitting efficiency. Experimental results demonstrate that the heterostructure synergistically reduces charge transfer resistance, increases exposure of active sites, and enhances oxygen gas evolution ability. Consequently, the V Se 2 / NiFe − LDH electrocatalyst demonstrated superior sustainability, maintaining an elevated current density (500 mA cm − 2 ) for over 50 h of continuous electrolysis without noticeable degradation. This research opens up new possibilities and shows that nano-compositing can be a good option for achieving efficient and durable electrocatalysts in alkaline water splitting, thereby contributing to sustainable hydrogen production. [Display omitted] • Facile hydro/solvothermal preparation of composites of NiFe-LDH and VSe 2. • Enhanced Oxygen and Hydrogen evolution were observed. • Decreased charge transfer resistance was noticed. • Durable up to about 50 h for overall water splitting at a high current density of 500 mA cm − 2. [ABSTRACT FROM AUTHOR]

Hydrogen, renowned for its abundance and versatility, stands as a significant green energy alternative, especially when produced through water electrolysis. In this study, 2D/2D van der Waals heterostructure with graphene and WS 2 monolayer (GW) is constructed as electrocatalyst for hydrogen evolution reaction (HER). The cohesive energy and the binding energy per area for the GW heterostructure are found to be −0.39 eV and −18.9 meV/Å2 which confirms the structural stability as well as the weak binding of two monolayers. Furthermore, ten 3d transition metals are introduced as single atom catalyst (SAC) in the GW heterostructure (TM@GW) to enhance the catalytic performance. The ΔG H* for all TM@GW shows that there is an enrichment in the HER performance by 47–96 % upon the introduction of SAC, showcasing the superiority of Zn@GW heterostructure with an overpotential of 80 mV and the lowest kinetic barrier of 0.51 eV for the Volmer-Tafel reaction. This investigation provides valuable insight for modeling both van der Waals heterostructures and SACs to enrich catalytic performance. [Display omitted] • HER performance of Graphene/WS 2 van der Waals heterostructure is studied using DFT. • HER performance of TM@GW heterostructure is enhanced by about 47–96%. • Zn@GW vdW heterostructure is found to lowest overpotential of 80 mV. • Zn@GW has the lowest kinetic barrier of 0.51 eV for the Volmer-Tafel reaction. [ABSTRACT FROM AUTHOR]

Developing high‐performance electrocatalysts for CO2 reduction reaction (CO2RR) is vital in achieving a carbon‐neutral society by converting CO2 into valuable chemicals. CO2RR electrocatalyst with lower overpotential, higher selectivity and wider working potential range is urgently desired, but it is still challenging to realize these factors simultaneously. Here, high‐performance bismuthene‐based electrocatalysts were synthesized by reducing bismuth precursors like BiCl3, BiBr3, and BiI3 in liquid phases. Especially, bismuthene‐I derived from BiI3 showed a nanosheet morphology (around four‐layer) with significantly enhanced (110) surfaces. It enabled an ultrawide potential window (0.7 V) for high formate selectivity (>90%) in a H‐type cell and achieved an ultralow potential (−0.46 V vs. reversible hydrogen electrode) to attain a current density of 200 mA cm−2 in a gas‐diffusion flow cell. The prominent long‐term operational capability of bismuthene‐I was demonstrated in both H‐type and gas‐diffusion cells. Density functional theory calculations revealed that bismuthene‐I possessed abundant topological Bi(110) surfaces states that can reduce the CO2RR overpotential, suppress the competitive hydrogen evolution reaction, and facilitate electron donation during CO2 electrocatalysis. The bismuthene‐I realized low overpotential, high selectivity and wide working potential range simultaneously for electrochemical CO2RR. This work unfolds the broader plausibility of facilely reducing precursors for the scalable fabrication of high‐performing CO2RR electrocatalysts. [ABSTRACT FROM AUTHOR]

The paper reports the development of Cu-doped NiCo 2 O 4 ternary inverse spinel oxides through microwave-assisted hydrothermal method as effective catalysts for alkaline hydrogen evolution reaction (HER). The effective and controlled doping of Cu to NiCo 2 O 4 lattice by the partial replacement of Ni2+/Ni3+ with Cu+/Cu2+ results in the fine-tuning of structural, morphological, and electronic characteristics, favourable for electrocatalytic HER. The study effectively correlates the influence of variation in the percentages of Cu-doping on the material properties and thereby the electrocatalytic characteristics. The experimental results indicate that Cu 0.10 Ni 0.90 Co 2 O 4 electrode having optimum Cu-doping (10%) as the best electrocatalyst with the lowest onset potential for hydrogen evolution (242.7 mV) and reduced overpotential (72.5 mV) values by following a Volmer – Heyrovsky mechanism during HER. The improvement in HER performance after Cu-doping is due to the generation of greater number of active sites and reduction in electronic band gap. The present work advantageously utilises the scope of microwave-assisted transition metal doping strategy to fine tune the physicochemical and electronic characteristics, favourable for electrocatalytic HER, and this may pave a new way for tuning the electrochemical properties of metal oxides for various applications. • Microwave-assisted hydrothermal synthesis is used effectively to develop Cu-doped NiCo 2 O 4. • Cu-doping to NiCo 2 O 4 lattice creates more oxygen vacancies and improves electronic conductivity. • Cu 0.10 Ni 0.90 Co 2 O 4 with 10% Cu-doping exhibits promising electrocatalytic activity towards HER. • Cu-doped NiCo 2 O 4 follows Volmer – Heyrovsky mechanism during alkaline HER. [ABSTRACT FROM AUTHOR]

The objective of this study was to report electrocatalytic activity of tin selenide (SnSe) for oxygen evolution process (OER) and hydrogen evolution reaction (HER). Simple and inexpensive SnSe thin films were deposited onto a steel substrate using an electrodeposition method. Orthorhombic SnSe required a low overpotential value of 325, 317, 314 mV for OER and a low overpotential value of 273, 219, 194 mV for HER for SnSe-1, SnSe-2, and SnSe-3 electrodes, respectively, to reach a current density of 10 mA/cm2. The thickness of thin film increased over time 50, 60, and 70 min for each successive SnSe-1 to SnSe-3 samples. SEM image indicated crystalline in nature with compact grain-like morphology on the entire surface of the substrate. The SnSe-3 sample displayed low Tafel slopes of 90 and 68 mV/dec for OER and HER, respectively. EDX showed that atomic percentage ratio of Sn: Se was 54:46 for SnSe-3 thin film. Overall results suggest that electrochemically synthesized SnSe is a promising candidate as an efficient electrocatalyst for overall water splitting. [Display omitted] • Electrodeposited SnSe thin films were successfully synthesized. • The influence of deposition time on catalytic performance was examined. • Electrocatalytic analysis of SnSe was performed to capabilities of OER and HER. • The catalytic activity exhibited stability over a period of 12 h. [ABSTRACT FROM AUTHOR]

Various strategies have been adopted to enhance the characteristics of the MoO 2 nanoparticles electrode structures. Meanwhile the alkaline medium exhibits the sluggish kinetic and an acidic medium can donate the excess protons to promote the hydrogen evolution reaction. The annealing temperature may sputter the environmental oxygen from the surface and enhance the characteristics of the electrocatalysts. MoO 2 nanoparticles have been synthesized successfully using the hydrothermal process; later on, the synthesized structure was treated at temperatures of 400 and 600 °C under the flow of N 2 gas for 6 h. The heat treatment process at 600 °C influenced the characteristics of MoO 2 nanoparticles and enhanced the electrical conductivity, electrochemical and specific surface area and mesoporous features of MoO 2 -600 nanoparticles. Owing to boosted characteristics, MoO 2 -600 nanoparticles reveal a good overpotential of 56 mV at the current density of 10 mA cm−2 in 0.5 M H 2 SO 4 due to the excess availability of the protons, which is better than pre-annealed MoO 2 -basic and MoO 2 -400 nanoparticles. MoO 2 -600 nanoparticles exhibit a good Tafel slope of 22 mV dec−1 and follow the Tafel mechanism, while MoO 2 -600 nanoparticles show a Tafel slope of 64 and 67 mV dec−1 in buffer solution and 1 M KOH electrolyte, respectively. Moreover, the turnover frequency of MoO 2 -600 nanoparticles has been found as 191 ms−1 at the fixed reversible hydrogen potential of 800 mV RHE in 0.5 M H 2 SO 4 , which is greater than the buffer solution and 1 M KOH electrolyte. The results indicate that MoO 2 -600 nanoparticles are an effective electrocatalyst for hydrogen evolution reactions. • The annealing temperature may sputter the environmental oxygen from the surface. • MoO 2 -600 nanoparticles exhibited a greater electrical conductivity area. • MoO 2 -600 nanoparticles reveal a good overpotential of 56 mV in 0.5 M H 2 SO 4. • MoO 2 -600 nanoparticles exhibit a good Tafel slope of 22 mV dec−1 in 0.5 M H 2 SO 4. • The electrocatalyst MoO 2 -600 nanoparticles showed a higher TOF of 191 m s−1. [ABSTRACT FROM AUTHOR]

Water splitting is considered a renewable and eco−friendly technique for future clean energy requirements to realize green hydrogen production, which is, to a large extent, hindered by the oxygen evolution reaction (OER) process. In recent years, two−dimensional (2D) carbon−based electrocatalysts have drawn sustained attention owing to their good electrical conductivity, unique physicochemical properties, and excellent electrocatalytic performance. Particularly, it is easy for 2D carbon−based materials to form nanocomposites, which further provides an effective strategy for electrocatalytic applications. In this review, we discuss recent advances in synthetic methods, structure−property relationships, and a basic understanding of electrocatalytic mechanisms of 2D carbon−based electrocatalysts for water oxidation. In detail, precious, non−precious metal−doped, and non−metallic 2D carbon−based electrocatalysts, as well as 2D carbon−based confined electrocatalysts, are introduced to conduct OER. Finally, current challenges, opportunities, and perspectives for further research directions of 2D carbon−based nanomaterials are outlined. This review can provide significant comprehension of high−performance 2D carbon−based electrocatalysts for water-splitting applications. [ABSTRACT FROM AUTHOR]

Herein, a novel Pt anchoring WO3 nanoarray catalyst is reported and its application as HzOR and HER bifunctional electrocatalysts which shown to have superior bifunctional performance for HzOR/HER under alkaline conditions. The Pt/WO3/NF requires an ultrasmall overpotential of 34.6 and 226.38 mV to achieve 10 and 100 mA cm−2 for the hydrazine oxidation reaction (HzOR), respectively. When used for HER-HzOR electrolysis, Pt/WO3/NF requires low voltages of 0.717 V and 1.049 V at 100 and 200 mA cm−2, respectively. [ABSTRACT FROM AUTHOR]

Low-cost and highly efficient cathode and anode materials are required for proton exchange membrane and alkaline water electrolyzers. The present work demonstrates the development of a bifunctional cathode and anode material for hydrogen and oxygen evolution reactions (HER/OER) in an alkaline environment. The bimetallic Ni–Mo selenide is fabricated over the MXene (Ti 3 C 2 T x) grown over the activated carbon fibers by an inexpensive, simple one-step and eco-friendly approach. The electrocatalyst NiMoSe/Ti 3 C 2 T x @CC is developed via a hydrothermal method wherein NiMoSe is observed to grow highly dense nanoporous structure as confirmed by various characterization techniques. Highest activity for HER is observed using NiMoSe/Ti 3 C 2 T x @CC with only overpotential of 203 mV at 10 mA cm−2 with low Tafel slope (45 mV dec−1). The catalyst is also proven to support OER activity with requirement of 320 mV as overpotential at 10 mA cm−2, thus better than commercial IrO 2 (η 10 = 380 mV). The Tafel slope obtained by NiMoSe/Ti 3 C 2 T x @CC for OER is found to be minimum (189 mV dec−1) along with a very low charge transfer resistance (3.04 Ω) and high electrochemical surface area (0.0378 mF cm−2). The NiMoSe/Ti 3 C 2 T x @CC is found to be highly stable for HER/OER with 1000 LSV cycles. The work highlights the development of a cost-effective and efficient Ti 3 C 2 T x (MXene) based bifunctional electrocatalyst for oxygen evolution and hydrogen evolution reactions (OER/HER) in an alkaline medium (1 M KOH). The bimetallic Ni–Mo selenide is fabricated over the MXene on the activated carbon fibers by an inexpensive, simple, one-step hydrothermal method. The highly dense nanoporous structure shows an overpotential of 203 mV at 10 mA cm−2 for HER in alkaline medium. The corresponding overpotential for OER is 320 mV which has been found better than commercial IrO 2 catalyst (η 10 = 380 mV). In addition, NiMoSe/Ti 3 C 2 T x @CC bears a high electrochemically active surface area (0.0378 mF cm−2), low charge transfer resistance (3.04 Ω), and high stability (1000 LSV cycles) for both OER and HER. [Display omitted] • Bifunctional NiMoSe/Ti 3 C 2 T x @CC was synthesized via one step hydrothermal route. • Overpotential (η 10) for HER was found to be 203 mV. • For OER, overpotential (η 10) was found 320 mV, better than commercial IrO 2. • 1000 LSV cycle and 30 h stability was conducted for HER and OER. [ABSTRACT FROM AUTHOR]

Graphitic carbon nitride (g-C3N4), as a carbon support material with excellent stability and abundant active sites, has found widespread applications in various fields, including photocatalytic water splitting, electrolysis of water, and CO2 reduction. Presently, research on the modification of g-C3N4 primarily focuses on atomic doping, defect engineering, and the decoration of metal nanoparticles. In this study, a method involving the high-temperature pyrolysis of a solution containing thiourea and urea was successfully employed to synthesize sulfur-doped porous g-C3N4 (S-C3N4) nanosheets. Subsequently, PtCu nanoparticles were loaded onto the S-C3N4 through a hydrothermal process. In the case of Pt loading of less than half of 20% Pt/C, this catalyst exhibited a low overpotential of only 10 mV at a current density of 10 mA cm−2, which is significantly better than the 35 mV overpotential of 20% Pt/C. Furthermore, after a long period of continuous current stability testing, the overpotential of the catalyst did not increase by more than 30 mV, demonstrating excellent stability. The porous S-C3N4 nanosheets possess a large specific surface area, providing abundant active sites for the HER reaction. This research introduces a fresh method for creating innovative catalysts based on Pt alloys supported by a carbon carrier. [ABSTRACT FROM AUTHOR]

We present a facile and scalable method to synthesize Pt/C catalysts with high Pt loading (10–30 wt.%) using sodium polyacrylate resin (PAANa) as a multifunctional agent. PAANa can absorb H 2 PtCl 6 solution and form a gel, which can be converted into Pt/C catalysts by pyrolysis. PAANa acts as a water absorber, a Pt stabilizer, and a carbon precursor. The optimized catalyst, pyrolyzed at 800 °C with a 20 wt.% Pt loading, demonstrates Pt nanoparticles measuring 3.5 nm in size. It exhibits excellent stability and achieves a low overpotential of 43 mV at a current density of 10 mA cm−2 for the hydrogen evolution in alkaline media. The enhanced catalytic activity is due to the combined influence of the nanoscale Pt particles, the higher degree of graphitization, and the porous carbon substrate with a large surface area. We also demonstrate the scalability of the method by producing 100 g of the catalyst in the laboratory. [Display omitted] • Using PAANa as a multifunctional agent solves challenge of synthesizing high Pt loading Pt/C. • Pt/C catalyst demonstrates excellent performance with low overpotential and high stability. • Scalable method enables synthesis of Pt/C (100 g) for potential industrial applications. [ABSTRACT FROM AUTHOR]

The electrocatalytic oxygen evolution reaction (OER) is an arduous step in water splitting due to its slow reaction rate and large overpotential. Herein, we synthesized glycerate-anion-intercalated nickel–iron glycerates (NiFeGs) using a one-step solvothermal reaction. We designed various NiFeGs by tuning the molar ratio between Ni and Fe to obtain Ni4Fe1G, Ni3Fe1G, Ni3Fe2G, and Ni1Fe1G, which we tested for their OER performance. We initially analyzed the catalytic performance of powder samples immobilized on glassy carbon electrodes using a binder. Ni3Fe2G outperformed the other NiFeG compositions, including NiFe layered double hydroxide (LDH). It exhibited an overpotential of 320 mV at a current density of 10 mA cm–2 in an electrolytic solution of pH 14. We then synthesized carbon paper (CP)-modified Ni3Fe2G as a self-supported electrode (Ni3Fe2G/CP), and it exhibited a high current density (100 mA cm−2) at a low overpotential of 300 mV. The redox peak analysis for the NiFeGs revealed that the initial step of the OER is the formation of γ-NiOOH, which was further confirmed by a post-Raman analysis. We extensively analyzed the catalyst's stability and lifetime, the nature of the active sites, and the role of the Fe content to enhance the OER performance. This work may provide the motivation to study metal-alkoxide-based efficient OER electrocatalysts that can be used for alkaline water electrolyzer applications. [ABSTRACT FROM AUTHOR]

The practical application of CO2 electroreduction to CO driven by renewable electricity should simultaneously meet the requirements of low overpotential, high CO faradaic efficiency (FE), and low cost. Herein, a new strategy is reported to construct a porous nanoflower Ni–Al NC catalyst with excellent catalytic activity via p–d orbital hybridization of Al and Ni. The optimized Ni–Al NC catalyst exhibits an outstanding CO2 electroreduction activity with the maximum CO FE of 98%, low onset potential of −0.5 V vs. RHE, and wide FECO plateau (>90% from −0.7 to −1.0 V vs. RHE), showing great promise for practical applications. The experimental results showed that the p–d hybrid Ni–Al NC catalyst not only enriched its reaction sites but also withstood potential changes in the highly selective reduction of CO2 to CO. This study provides a catalyst design strategy for the efficient electrocatalytic reduction of CO2 to CO under varying potentials. [ABSTRACT FROM AUTHOR]

Designing efficient electrocatalysts for hydrogen generation is desirable for electrochemical water splitting and fuel cells as they are a part of clean and sustainable energy system. Here, we are reporting the utilization of clean method for the production of platinum deposited chromium disulphide (CrS 2) particles and their application for hydrogen generation via photo-assisted electrochemical water splitting. Photoelectrochemical studies of CrS 2 show a close to zero onset potential, ultralow overpotential (8.3 mV), small Tafel slope (54 mV/decade), and low impedance (1.8 Ω) in acidic media. The chronoamperometric study of prepared catalyst reveals that it is sustainable as having a long-term stability. The post electrochemical study of electrode surface reveal the presence of traces of Pt deposited over CrS 2. The detailed compositional analysis of electrolyte has also been performed. This study opens up a pathway for electrochemically modifying the composition of the catalysts for harnessing their potential as efficient electrocatalyst during water splitting. [Display omitted] • Monoclinic CrS 2 Particles were obtained via one step pyrolysis method. • Platinum has been deposited electrochemically on CrS 2. • Prepared nanocomposites show excellent HER activity at near-zero onset potential. [ABSTRACT FROM AUTHOR]

The metal–organic framework (MOF) materials with large active sites and excellent catalytic properties have attracted widespread attention and are expected to be promising for oxygen evolution reaction (OER) for water splitting. Herein, we report a new and efficient heterogeneous nanostructure OER system constructed by a bimetallic 2D-layered porous metal–organic framework (Cu/Ni-MOF) and semiconductor nano-TiO2 particles. The bimetallic MOF can control its porous layered morphology by adjusting the ratio of surfactants. The OER performance of the hybrid system can be enhanced by introducing nano-TiO2 particles, and the performance of reducing the overpotential value is about 2.4 times higher than the pure Cu/Ni-MOF. Under illumination, the overpotential (η=10) is only 79 mV, which is much lower than the pure Cu/Ni-MOF (189 mV). At the same time, it can still maintain a low overpotential value of 168 mV after a 24 h stability test. This study also briefly tested the catalytic performance of the material in hydrogen evolution reaction (HER), and under the illumination conditions, the overpotential (η = 10) is 209 mV. Furthermore, it revealed the key role of bimetallic synergy and P–N heterojunction (via electrical and simulated photo-excited electrons) in boosting the OER performance of the system. The finding and proposed concept provide a new approach for synthesizing multi-metal MOFs and combining them with semiconductors to enhance the photoelectrochemical water splitting and open a new avenue to design high-performance MOF heterojunctions for photo-electrocatalysis. [ABSTRACT FROM AUTHOR]

MoS 2 nanostructures are famous electrocatalysts in hydrogen evolution reaction (HER). The presence of graphene was already reported to boost the electrocatalytic activity of MoS 2. This work reports the influence of Sulphur deficiency and economically synthesizable green carbon dot (GCD) incorporation into hydrothermally synthesized MoS 2 nanostructures on the electrocatalytic activity of HER. All as-synthesized nanocatalysts are Sulphur deficient (MoS 2−x and GCD-MoS 2−x) and exhibited superior HER activity as compared to commercial MoS 2. MoS 2−x 220 exhibited a Tafel slope of 43 mV/Dec indicates the reaction mechanism as Volmer-Heyrovsky with Heyrovsky as rate determining step. Best electrocatalytic parameters are observed for the same catalyst with overpotential: 247 mV at 10 mA/cm2, Turnover frequency: 0.42 s−1, double layer capacitance: 23.8 mF/cm2 and electrochemically active surface area: 595/cm2. The obtained preferable HER parameters suggest that Sulphur deficiency and incorporation of GCD in MoS 2 are playing a vital role in HER electrocatalysis. [Display omitted] • HER activity of MoS 2 nanostructures on sulphur deficiency and GCD incorporation. • The effect of electrocatalytic activity of MoS 2 in the presence of GCD: A novel study. • Detailed examination of HER mechanism. • MoS 2−x 220 exhibited best overpotential:247 mV, Tafel slope:43 mV/Dec, TOF:0.42 s−1. [ABSTRACT FROM AUTHOR]

Recent experiments have demonstrated that 1T phase of transition-metal dichalcogenides exhibits superior electro-catalytic activity for hydrogen evolution reaction (HER). Herein, we compare the HER performance of as obtained 2H-phase MoSe 2 (bare) with hydrothermally synthesized 1T-2H mixed phase MoSe 2 and its composites with reduced graphene oxide. Obtained MoSe 2 /rGO composite has displayed a Tafel slope of 55 mV dec−1 compared with mixed-phase (113 mV dec−1) and 2H–MoSe 2 (125 mV dec−1, bare). Composite of MoSe 2 with very small amount of rGO has shown increased HER activity with low overpotential (88 mV at 10 mA cm−2), smaller Tafel slope, longer durability and high value of turn over frequency. The weight ratio between MoSe 2 and rGO is crucial in determining the HER performance of the composite. The Present work offers a facile and attractive methodology for enhancing the HER performance of 2D materials-based electrocatalysts. • MoSe 2 /rGO composites were synthesized via facile hydrothermal route. • Presence of 1T/2H–MoSe 2 phase improved the catalytic properties. • Weight ratio between MoSe 2 and rGO plays a key role in HER kinetics. • MoSe 2 /rGO composite with ideal weight ratio possesses lower Tafel slope (55 mVdec−1). • Lower overpotential and charge transfer resistance give smaller Tafel slope in composite. [ABSTRACT FROM AUTHOR]

An important, yet difficult problem is the rational design and controlled production of an electrocatalyst for hydrogen evolution reaction (HER) using graphene-based bimetallic sulphide. Here, a novel electrocatalyst for HER was designed and created using a spherical-shaped structure grown on a graphene sheet with a conductive Cu-CoS2 support (rGO@CuCoS2). It takes advantage of the synergistic effect between the copper and cobalt sulphide phases, the naturally low resistance of the bimetal substrate, and the uniform spherical structure. With overpotentials of 84 mV at a current density of 10 mA cm−2 in alkaline electrolytes, the self-supported rGO@CuCoS2 composite catalyst demonstrates outstanding electrocatalytic activity for HER in an alkaline pH range, respectively. The created rGO@CuCoS2 catalyst impressively exhibits steady electrocatalytic activity and high durability in HER processes. The electrocatalytically accessible sites were also discovered to be 15.02 x 1017 sites at a 5 mV s−1 scan rate. This novel mix of methods is intended to offer a workable plan for the advancement of human energy and is promising much beyond the realm of water electrolysis. [ABSTRACT FROM AUTHOR]

In this study, the pristine MgO, MgO/CNT and Ni-MgO/CNT nanocomposites were processed using the impregnation and chemical vapor deposition methods and analyzed for hydrogen evolution reaction (HER) using the electrochemical water splitting process. Furthermore, the effect of nickel on the deposited carbon was systematically elaborated in this study. The highly conductive carbon nanotubes (CNTs) deposited on the metal surface of the Ni-MgO nanocomposite heterostructure provides a robust stability and superior electrocatalytic activity. The optimized Ni-MgO/CNT nanocomposite exhibited hierarchical, helical-shaped carbon nanotubes adorned on the surface of the Ni-MgO flakes, forming a hybrid metal–carbon network structure. The catalytic HER was carried out in a 1M alkaline KOH electrolyte, and the optimized Ni-MgO/CNT nanocomposite achieved a low (117 mV) overpotential value (ɳ) at 10 mA cm−2 and needed a low (116 mV/dec) Tafel value, denotes the Volmer–Heyrovsky pathway. Also, the high electrochemical active surface area (ECSA) value of the Ni-MgO/CNT nanocomposite attained 515 cm2, which is favorable for the generation of abundant electroactive species, and the prepared electrocatalyst durability was also performed using a chronoamperometry test for the prolonged duration of 20 h at 10 mA cm−2 and exhibited good stability, with a 72% retention. Hence, the obtained results demonstrate that the optimized Ni-MgO/CNT nanocomposite is a highly active and cost-effective electrocatalyst for hydrogen energy production. [ABSTRACT FROM AUTHOR]

Exploring non-noble metal dual-functional electrocatalysts with high activity and stability for water splitting is highly desirable. In this study, using zeolitic imidazolate framework-L (ZIF-L) nanoarrays as the precursor, manganese oxide-decorated porous nickel–cobalt phosphide nanosheet arrays have been prepared on nickel foam (denoted as MnOx/NiCoP/NF) through cation etching, phosphorization and electrodeposition, which are utilized as an efficient dual-functional electrocatalyst for overall water splitting. The hierarchical porous nanosheet arrays provide abundant active sites for the electrochemical process, while the MnOx modification induces strong interfacial interaction, benefiting charge transfer. Thus, the MnOx/NiCoP/NF exhibits excellent electrocatalytic activity toward the hydrogen evolution reaction (HER, overpotential of 93 mV at 10 mA cm−2), oxygen evolution reaction (OER, overpotential of 240 mV at 10 mA cm−2) and overall water splitting (cell voltage of 1.59 V at 10 mA cm−2). Furthermore, it shows superior stability during continuous overall water splitting for 200 h. This work provides a simple and effective approach for developing efficient non-noble metal dual-functional catalysts for overall water splitting. [ABSTRACT FROM AUTHOR]

The electrocatalytic splitting of water to produce hydrogen is regarded as an efficient and promising strategy but is limited by its large overpotential; thus, a highly efficient electrocatalyst is urgently needed. Mixed metal doping is an important strategy in defect engineering because the heteroatoms can change the intrinsic structure to form defects by affecting the atomic coordination mode and adjusting the electronic structure, which is often accompanied by morphological changes. Herein, two-dimensional layered bimetallic Co–pydc containing axially coordinated water molecules was selected by producing surface defects through Fe doping in Co centers as bifunctional electrocatalysts for OER and HER. The optimized Co0.59Fe0.41–pydc possesses outstanding OER performance with the lowest overpotential of 262 mV to reach j = 10 mA cm−2, and Co0.75Fe0.25–pydc possesses superior HER performance with the lowest overpotential of 96 mV at j = 10 mA cm−2. Furthermore, the overall water splitting device assembled with Co0.59Fe0.41–pydc@NF//Co0.59Fe0.41–pydc@NF affords a current density of 10 mA cm−2 at only 1.687 V. This work emphasizes the surface defects formed by tuning the electronic structure of metal centres accompanied with morphological changes of bimetallic dopants for efficient overall water splitting. [ABSTRACT FROM AUTHOR]

Single-atom catalysts (SACs), distinguished by their exceptional atomic efficiency and modifiable coordination structures, find wide-ranging applicability, notably in the context of the hydrogen evolution reaction (HER). Herein, we synthesized a Ti3C2Tx-based Ni single-atom catalyst (Ni SA@N-Ti3C2Tx) by immersing a single Ni atom into the Ti vacancies of Ti3C2Tx and using a N-doping strategy. X-Ray adsorption fine structure revealed the formation of local Ni-N1C1 and an unsaturated C–Ni–N bridge configuration for isolated Ni species. Moreover, Ni SA@N-Ti3C2Tx exhibited an excellent HER performance with an overpotential of 63 mV at 10 mV cm−2. This work could enable use of MXene-based SACs in the HER. [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 construction of efficient, sustainable, and low-cost nonprecious metal electrocatalysts for oxygen evolution reaction (OER) is necessary for the realization of electrocatalytic overall water splitting. Herein, the PW 6 Mo 6 /ZIF-67@NF is prepared using a simple coprecipitation method. Characterization results indicate that the PW 6 Mo 6 induces the exposure of Co nodes in ZIF-67, which can act as catalytic active sites for OER. Meanwhile, the introduction of PW 6 Mo 6 improves the conductivity and electrochemical active surface area of ZIF-67, which further enhances the OER performance. The electrochemical test results show that the PW 6 Mo 6 /ZIF-67@NF exhibit an ultralow overpotential of 201 mV at 10 mA cm−2 and a small Tafel slope of 55 mV dec−1 for OER, which is lower than that of ZIF-67@NF (329 mV, 286 mV dec−1). Our study demonstrates the potential of polyoxometalate and ZIF composites to decrease the barriers of OER and provides a feasible approach for exploring economical and practical electrocatalysts. The etching of PW 6 Mo 6 induces the exposure of Co active sites in ZIF-67, thereby PW 6 Mo 6 /ZIF-67@NF exhibit an ultralow overpotential of 201 mV at 10 mA cm−2 and a small Tafel slope of 55 mV dec−1 for OER. [Display omitted] • The PW 6 Mo 6 /ZIF-67@NF with exposed Co nodes was successfully prepared using a coprecipitation method. • The introduction of PW 6 Mo 6 improved the conductivity and electrochemical active surface area of ZIF-67. • The ZIF-67 framework prevents the dissolution of PW 6 Mo 6 in the electrolyte, thus increasing the stability. • The PW 6 Mo 6 /ZIF-67@NF exhibited an ultralow overpotential and a small Tafel slope for OER. [ABSTRACT FROM AUTHOR]

Constructing bifunctional electrocatalysts is essential for efficient water splitting. Rational interface engineering is an effective method for modifying active sites and promoting electronic charge transfer, resulting in improved water splitting efficiency. In this study, we designed a metal-free, 2D structure of graphene and boron nitride (h-BN). 2D stacking of two different layers generated abundant interfaces as well as huge electrochemical active sites. As a result, the graphene/h-BN stacked structure has a very low overpotential of 28 mV (for 10 mA/cm2 current density) for hydrogen evolution. At the same time, a significantly low overpotential of 360 mV (for 50 mA/cm2 current density) was achieved for oxygen evolution. The stacked structure of graphene/h-BN has been effectively utilized as a promising cathode and anode in a two-electrode system for accomplishing overall water splitting. Thus, our investigation suggests that rational construction of heterogeneous interfaces by stacking different 2D nanostructures can accelerate the overall water splitting by maximizing the electrochemical performance. [Display omitted] • Graphene layer was engineered by stacking h-BN • 2D stacking generated abundant interfaces as well as huge electrochemical active sites • A very low overpotential of 28 mV (for 10 mA/cm2 current density) for hydrogen evolution • Overpotential for OER was significantly low 360 mV (for 50 mA/cm2 current density) [ABSTRACT FROM AUTHOR]

In electrocatalytic water decomposition technology, particularly in alkaline solutions, hydrogen evolution with transition metal catalysts has received significant interest. In this study, an efficient HER electrocatalyst with nickel foam base was produced by electrodeposition. Compared with other catalysts, the synthesized CoMo@EDTA electrocatalyst showed significant electrocatalytic activity against HER in alkaline electrolytes. By changing the type of complexing agent, it is found that the overpotential is the lowest after adding EDTA-2Na in 1 mol/l NaOH solution. The overpotential of the CoMo@EDTA catalyst is 29 mV, When the current density is −10 mA/cm2, The outstanding HER performance of CoMo@EDTA electrocatalysts is mainly due to the interaction of molybdenum and cobalt and the effect of complexing agents. After the stability measurement for up to 6 h, the catalyst has a minimal overpotential loss, indicating that the catalyst has excellent stability. This work provides a useful pathway for the application of transition metals in hydrogen evolution electrocatalysts. [Display omitted] • The catalyst preparation steps are simple and the time is short (40 min). • The prepared catalyst has low overpotential (29 mV) and low tafel slope. • The prepared catalyst has the characteristics of strong stability (6 h without obvious overpotential loss). • We analyzed the effects of different complexing agents on the catalyst and found that EDTA-2Na had the best effect. [ABSTRACT FROM AUTHOR]

Designing an ideal bi-functional electrocatalyst for the overall water splitting plays significant function in alternative energy construction. Based on the previous literatures, the Co 3 O 4 /g-C 3 N 4 nanocomposite has been investigated as the bi-functional electrocatalyst. In the present study, the facile hydrothermal route was approached to synthesize the Co 3 O 4 /g-C 3 N 4 nanocomposite to enhance the electrocatalytic activity towards oxygen evolution reaction (OER) and hydrogen evolution reaction (HER). Further, Co 3 O 4 /g-C 3 N 4 electrochemical analysis was undergone in an aqueous alkaline solution of 1 M potassium hydroxide for both OER and HER. High electrocatalytic nature of prepared Co 3 O 4 /g-C 3 N 4 nanocomposite delivered the low 170 mV overpotential value and 151 mV at 20 mA/cm2 with Tafel values 188 mV/dec and 176 mV/dec for OER and HER. Also electrochemical surface area (ECSA) of prepared Co 3 O 4 /g-C 3 N 4 nanocomposite was estimated from double layer capacitance (C dl) values, and calculated ECSA values are 0.027 cm2 and 0.097 cm2 for OER and HER respectively. The resultant Co 3 O 4 /g-C 3 N 4 nanocomposite reached the low charge transfer resistance value of 15.9 Ω for OER and 22.7 Ω for HER which could acts as strong parameter to improve conductivity of the prepared electrode for both half reactions. Along with that, stability of Co 3 O 4 /g-C 3 N 4 nanocomposite exhibits the outstanding performance at the current density of 10 mA/cm2 with only minimum amount of loss even after 16 h for both OER and HER. Hence, the synthesized Co 3 O 4 /g-C 3 N 4 nanocomposite was act as an optimistic choice of the bi-functional electro catalyst for sustainable energy production. • Attempted Co 3 O 4 /g-C 3 N 4 for bi-functional electrochemical water splitting. • Co 3 O 4 /g-C 3 N 4 delivered 170 and 151 mV at 20 mA/cm2 with low Tafel values 188 and 176 mV/dec for OER and HER. • Stability of Co 3 O 4 /g-C 3 N 4 for long duration up to 16 h results 74% and 60% retention for both OER and HER. • Co 3 O 4 /g-C 3 N 4 was optimistic choice of the bi-functional electrocatalyst. [ABSTRACT FROM AUTHOR]

An innovative strategy has been developed to activate the basal planes in molybdenum disulfide (MoS2) to improve their electrocatalytic activity by controlling surface electron accumulation (SEA) through aging, annealing, and nitrogen-plasma treatments. The optimal hydrogen evolution reaction (HER) performance was obtained on the surface treated with nitrogen-plasma for 120 s. An overpotential of 0.20 V and a Tafel slope of 120 mV dec−1 were achieved for the optimized condition. The angle-resolved photoemission spectroscopy measurement confirmed the HER efficiency enhanced by the SEA conjugated with the sulfur vacancy active sites in the MoS2 basal planes. This study provides new insight into optimizing MoS2 catalysts for energy applications. [ABSTRACT FROM AUTHOR]

The free standing CoFe@PANI bifunctional electrocatalyst display high electrocatalytic activity for OER (overpotential of 230 mV @10 mA cm−2) and MOR (specific current density of 120 mA cm−2) in alkaline medium. [Display omitted] Developing inexpensive, highly electrochemically active, and stable catalysts towards electrochemical studies remains challenge for researchers. In this regard, binder-free CoFe@PANI composite electrocatalyst is deposited on nickel foam (NF) substrate via successive electrodeposition of polyaniline (PANI) and CoFe-LDH at Room temperature (RT). As deposited binder-free CoFe@PANI electrocatalyst displays high electrocatalytic activity towards oxygen evolution reaction (OER) and methanol oxidation reaction (MOR) in alkaline media. In CoFe@PANI structure, interfacing of high-electron conducting PANI establishes strong interconnection with CoFe-LDH by tuning electronic structures, which accelerates the electrochemical performance towards OER and MOR. For OER, CoFe@PANI requires low overpotential (η 10) of 237 mV to reach current density (I d) of 10 mA cm−2 and displays low Tafel slope value of 46 mV dec−1 in 1 M KOH solution. Also, it displayed specific I d of 120 mA cm−2, when it was tested for MOR in 1 M KOH with 0.5 M methanol solution. The superior electrocatalytic activity of CoFe@PANI is mainly ascribed to high electrochemical active surface area (ECSA), abundant active sites and fast electron transfer between electrocatalyst and electrode surface. Of note, the current work may open new era for design and development of non-precious highly active and stable hybrid electrocatalysts at RT for various applications. [ABSTRACT FROM AUTHOR]

It is generally known that the hydrogen binding strength with active site guarantees the intrinsic catalytic performance toward hydrogen evolution reaction (HER). A moderate binding strength is requirable to achieve a robust HER electrocatalyst. In this work, we report a facile methodology to balance the hydrogen adsorption/desorption capability of metallic Rh by downshift in d band center via a partial sulfurization to construct Rh–Rh 2 S 3 heterostructure. The downshift in d band center of Rh results in weakening the overly strong hydrogen adsorption to a balanced level. Thereby, Rh–Rh 2 S 3 exhibits large decrements (67.2 mV and 92.2 mV) in overpotential at 100 mA cm−2 in acidic HER catalysis than Rh and Rh 2 S 3. Moreover, the merit of modulation in d band center is also reflected by alkaline HER. The overpotential at 100 mA cm−2 for Rh–Rh 2 S 3 is substantially decreased by 117.9 mV and 74.9 mV compared to Rh 2 S 3 and Rh. Additionally, a 3.3-time higher mass activity at −80 mV vs. RHE is achieved for Rh–Rh 2 S 3 with relative to commercial Pt/C. • Rh–Rh 2 S 3 heterostructure is synthesized via partial sulfurization. • Rh–Rh 2 S 3 exhibits a 3.3-time higher HER activity than Pt/C. • d band center of Rh was downshifted by introduction of Rh 2 S 3. [ABSTRACT FROM AUTHOR]

Heterostructures based on transition metal chalcogenides/oxides have gained significant interest in the application of electrochemical hydrogen evolution reaction (HER) due to their distinct characteristics and excellent electrocatalytic activity. Herein, we developed an earth-abundant, low-cost, and light-sensitive CuS/NiO (CSNO) heterostructure electrocatalyst via a facile co-precipitation method and fabricated it on silver-modified conducting cellulose paper for HER. Under all pH level, the performance of the visible light-sensitive HER catalyst has been examined. With the illumination of light, HER performance at all pH, which conserves energy has been seen. In basic media, the value of overpotential was improved to −290 mV vs RHE at 20 mA/cm2 under light-illuminating conditions. Similarly, with light illumination, the overpotential of the CSNO10/Ag- modified paper is reduced to −363 mV and −312 mV vs RHE in an acidic and in a near-neutral medium, respectively. In addition to that, the values of the Tafel slopes and charge-transfer resistance also decreased indicating relatively faster HER kinetics in the presence of light at all pH levels. Also, The CSNO10 electrode exhibits stability of more than 24 h in 1 M PBS with an overpotential of −368 mV vs RHE at 20 mA/cm2. The overall performance of the CuS/NiO heterostructure is a good sign to be explored it as a low-cost and efficient electrocatalyst for the large-scale production of green hydrogen (H 2). • We developed a light-sensitive CuS/NiO heterostructure electrocatalysts. • CSNO electrocatalyst shows pH universal HER performance. • CSNO shows an overpotential of −413 mV and −363 mV in light and dark. • CSNO electrocatalyst exhibits excellent stability upto 24 h. [ABSTRACT FROM AUTHOR]

One of the promising technologies for green hydrogen production is seawater electrolysis using an anion exchange membrane (AEM) electrolyzer. To overcome the use of precious metal catalysts, an alternate non-noble metal catalyst is urgently required to lower the operating cost of the electrolyzer. In this work, a novel high entropy metal oxide @ graphene oxide (HEMO@GO) was synthesized and explored as a bi-functional electrocatalyst for direct seawater electrolysis. The materials characterizations such as X-ray diffraction, Raman spectroscopy, scanning electron microscope with energy dispersive X-ray analysis, high-resolution transmission electron microscope, and X-ray photoelectron spectroscopy confirmed the formation of the HEMO@GO. The electrochemical seawater splitting was examined both in half-cell and full-cell configurations. It turned out that the HEMO@GO electrocatalyst could reach a current density of 10 mA cm−2 at a low overpotential of −482 mV for hydrogen evolution reaction (HER) and 597 mV for oxygen evolution reaction (OER) in the seawater. The full-cell electrolyzer exhibited a maximum current of 0.19 A at 3 V in the seawater. The homemade AEM seawater electrolyzer was demonstrated to operate at a generation rate of 32 mL h-1 at 2 V. Such a good performance was attributed to the HEMO grain's nature which acted as reaction centers, while the GO provided more contact area with the electrolyte that led to lower overpotential and high exchange current density. [Display omitted] • HEMO@GO as a bifunctional electrocatalyst was studied in half cell and full cell. • Low overpotentials of −482 mV for HER and 597 mV for OER in seawater at 10 mA cm−2. • GO provided large contact area and HEMO as reaction centers for HER/OER. • Green hydrogen was produced using a laboratory proto-type AEM electrolyzer. • A maximum current of 0.19 A at 3.0 V in the seawater using the electrolyzer. [ABSTRACT FROM AUTHOR]

Designing cost‐effective alkaline water‐splitting electrocatalysts is essential for large‐scale hydrogen production. However, nonprecious catalysts face challenges in achieving high activity and durability at a large current density. An effective strategy for designing high‐performance electrocatalysts is regulating the active electronic states near the Fermi‐level, which can improve the intrinsic activity and increase the number of active sites. As a proof‐of‐concept, it proposes a one‐step self‐assembly approach to fabricate a novel metallic heterostructure based on nickel phosphide and cobalt sulfide (Ni2P@Co9S8) composite. The charge transfer between active Ni sites of Ni2P and Co─Co bonds of Co9S8 efficiently enhances the active electronic states of Ni sites, and consequently, Ni2P@Co9S8 exhibits remarkably low overpotentials of 188 and 253 mV to reach the current density of 100 mA cm−2 for the hydrogen evolution reaction and oxygen evolution reaction, respectively. This leads to the Ni2P@Co9S8 incorporated water electrolyzer possessing an ultralow cell voltage of 1.66 V@100 mA cm−2 with ≈100% retention over 100 h, surpassing the commercial Pt/C║RuO2 catalyst (1.9 V@100 mA cm−2). This work provides a promising methodology to boost the activity of overall water splitting with ultralow overpotentials at large current density by shedding light on the charge self‐regulation of metallic heterostructure. [ABSTRACT FROM AUTHOR]