Promising Hydrogen Evolution Reaction Research Articles

A Molecular Engineered Strategy to Remolding Architecture of RuP2 Nanoclusters for Sustainable Hydrogen Evolution

AbstractTransition metal phosphides (TMPs) are promising hydrogen evolution reaction (HER) electrocatalysts, but the unsatisfying activity and durability at industrial‐scale current densities hinder their application. Downsizing TMPs to nanoclusters can substantially enhance their activity; yet, the high surface free energy tends to initiate agglomeration thereby limiting their service life. Herein, a molecular engineering strategy to synthesize robust sulfur‐doped RuP2 (S‐RuP2) nanoclusters, which can continuously provide ampere‐level current densities of 1.0, 2.0, and 3.0 A cm−2 for at least 480 h with low overpotentials of 55.6 ± 1.0, 90.6 ± 1.2, and 122.8 ± 1.0 mV, respectively, is proposed. In particular, it exhibits a remarkable charge transfer amount (representing a long service life), outperforming all reported alkaline HER electrocatalysts. Remoulding the RuP2 architecture by sulfur atom can significantly lift the d‐band center of Ru and the p‐band center of P, therefore strengthening the adsorption of H2O, H, and OH to reduce the barriers of water dissociation and H migration. The authors‘ research unveils the enormous potential of molecule‐based porous materials for designing high‐performance nano‐structured catalysts.

Revealing the Role of Mo Leaching in the Structural Transformation of NiMo Thin Film Catalysts upon Hydrogen Evolution Reaction.

NiMo alloys are considered highly promising non-noble Hydrogen Evolution Reaction (HER) catalysts. Besides the synergistic effect of alloying elements, recent attention is drawn to the Mo leaching from the catalyst. This work investigates the role of Mo in NiMo alloys during HER, aiming to understand the interplay between compositional, structural, and electronic factors on the activity, and their effects on the electrode material and catalyst properties. For this purpose, sputter-deposited low roughness NixMo100-x thin films are produced. The investigation of catalyst performance depending on their chemical composition shows a volcano-shaped plot, peaking for the Ni65Mo35 alloy with the highest intrinsic activity in alkaline HER. A comprehensive electrode surface analysis combining transmission electron microscopy, X-ray photoelectron spectroscopy and atomic force microscopy identifies the leaching of Mo on a structural level and indicates the formation of a Ni(OH)2-rich surface area. The ultimate surface characteristics of the NiMo catalysts depend on the initial composition and the electrochemical procedure. Based on the findings, it conclude that the observed catalytic properties of NiMo alloys in HER are determined by a complex interplay of increasing roughness, available surface species and their synergies. The leaching of Mo has a proven structural effect and is considered one of several factors contributing to the enhanced catalyst activity.

Water splitting by electrodepositing Ni–Co on graphite rod: Low-cost, durable, and binder-free electrocatalyst

This research looks at NiCo-based electrocatalytic improvements for hydrogen evolution reaction (HER) and oxygen evolution reaction (OER). The technique of synthesis, which uses cyclic voltammetry (CV) on the rod of graphite as substrate, provides a unique one-step electrochemical approach. The best conditions for effective catalyst production were discovered by fine-tuning parameters such as cycle numbers, scan speed, and Ni:Co concentration ratios. The major findings indicate that the enhanced Nickel–Cobalt film on a graphite rod demonstrates promising HER performance. Notably, it exhibits moderate overvoltage of −255 mV and −403 mV at current densities of 10 mA cm⁻2 and 100 mA cm⁻2, respectively. Furthermore, the Nickel–Cobalt electrocatalyst produced requires just 380 mV overvoltage to achieve 10 mA cm−2 current density, showing good efficiency of this electrode in OER. This study highlights its high stability, activity, and improved kinetics, attributing these characteristics to new microstructures, a binder-free electrodeposition procedure, and the combined benefits of Nickel and Cobalt. The proposed Nickel–Cobalt electrode, developed through a simple and cost-effective electrochemical deposition, demonstrates high efficiency for both HER and OER, making it a promising candidate for sustainable hydrogen generation.

Tuning the Local Environment of Pt Species at CNT@MO2-x (M = Sn and Ce) Heterointerfaces for Boosted Alkaline Hydrogen Evolution.

As the most promising hydrogen evolution reaction (HER) electrocatalysts, platinum (Pt)-based catalysts still struggle with sluggish kinetics and expensive costs in alkaline media. Herein, we accelerate the alkaline hydrogen evolution kinetics by optimizing the local environment of Pt species and metal oxide heterointerfaces. The well-dispersed PtRu bimetallic clusters with adjacent MO2-x (M = Sn and Ce) on carbon nanotubes (PtRu/CNT@MO2-x) are demonstrated to be a potential electrocatalyst for alkaline HER, exhibiting an overpotential of only 75 mV at 100 mA cm-2 in 1 M KOH. The excellent mass activity of 12.3 mA μg-1Pt+Ru and specific activity of 32.0 mA cm-2ECSA at an overpotential of 70 mV are 56 and 64 times higher than those of commercial Pt/C. Experimental and theoretical investigations reveal that the heterointerfaces between Pt clusters and MO2-x can simultaneously promote H2O adsorption and activation, while the modification with Ru further optimizes H adsorption and H2O dissociation energy barriers. Then, the matching kinetics between the accelerated elementary steps achieved superb hydrogen generation in alkaline media. This work provides new insight into catalytic local environment design to simultaneously optimize the elementary steps for obtaining ideal alkaline HER performance.

Synergetic Catalytic Effect between Ni and Co in Bimetallic Phosphide Boosting Hydrogen Evolution Reaction.

The application of electrochemical hydrogen evolution reaction (HER) for renewable energy conversion contributes to the ultimate goal of a zero-carbon emission society. Metal phosphides have been considered as promising HER catalysts in the alkaline environment, which, unfortunately, is still limited owing to the weak adsorption of H* and easy dissolution during operation. Herein, a bimetallic NiCoP-2/NF phosphide is constructed on nickel foam (NF), requiring rather low overpotentials of 150 mV and 169 mV to meet the current densities of 500 and 1000 mA cm-2, respectively, and able to operate stably for 100 h without detectable activity decay. The excellent HER performance is obtained thanks to the synergetic catalytic effect between Ni and Co, among which Ni is introduced to enhance the intrinsic activity and Co increases the electrochemically active area. Meanwhile, the protection of the externally generated amorphous phosphorus oxide layer improves the stability of NiCoP/NF. An electrolyser using NiCoP-2/NF as both cathode and anode catalysts in an alkaline solution can produce hydrogen with low electric consumption (overpotential of 270 mV at 500 mA cm-2).

Enhanced electrochemical performances of SrMoO4/MWCNT-PVP nanocomposites as electrocatalyst for hydrogen evolution reaction

In this work, we have successfully synthesized the cost-effective, abundant in nature and environmentally friendly SrMoO4/MWCNT-PVP by using the co-precipitation technique for hydrogen evolution reaction (HER). Prepared nanocomposites were characterized by XRD, which confirms the formation of tetragonal structure of SrMoO4 and indexed with JCPDS (01-074-3912). Raman spectra confirm the combination of SrMoO4 with carbon composite (verified by D and G band 1.02 ID/IG ratio) and its functional group was further analyzed with the help of FTIR spectra. Synthesized product morphology was characterized by using SEM and TEM images, which confirms formation of well-defined dumb-bell shaped nanostructures with the combination of carbon nanotube and also it further confirms the formation of polycrystalline nature of the material. The elemental composition was analyzed by EDS images, which confirms the occurrence of Sr, Mo, O, and C in an appropriate form with a uniform distribution, respectively. MWCNT in SrMoO4 incorporation led to decrease overpotential of 204 mV and 110 mV/dec Tafel slope of the material, which was examined by the LSV curves and Tafel plot analysis. Electrochemical impedance spectroscopy was also investigated, and it delivered the small charge-transfer resistance of 248 Ω, which further supporting the HER analysis and denoting the promising HER kinetics. Therefore, our work unlocks a new path for the properly tuned nanostructured morphology of metal oxide with carbon composite for electrochemical hydrogen evolution reaction application.

Surface-sulphurated nickel–molybdenum alloy film as enhanced electrocatalysts for alkaline overall water splitting

Nickel-molybdenum (NiMo) alloys are a kind of promising HER electrocatalysts to supersede precious metal based materials due to their highly active hydrogen evolution reaction (HER) kinetics in alkaline solution. However, the poor stability of NiMo, caused by the Mo dissolution mainly due to the thermodynamically instability of Mo in alkaline media, significantly limits its practical applications. Herein, a facile strategy is developed to modify the surface of the electrodeposited NiMo alloy film via a simple surface sulphuration treatment. Material characterizations show that the NiS homogeneously covers the surface of the NiMo alloy, resulting in a NiS/NiMo heterostructure. Electrochemical measurements show that the NiS/NiMo heterostructure exhibits outstanding HER activity (η-10 mA cm-2 = 77 mV) and good stability for 24 h stability test. Surprisingly, the heterostructure also displays excellent OER kinetics by delivering an ultra-low overpotential of 245 mV (10 mA cm−2). The constructed electrolyzer with NiS/NiMo acted as both cathode and anode needs only 1.547 V to power the water splitting at 10 mA cm−2. The formation of heterostructure and the enhanced electrochemically active surface area are responsible for the exceptional HER/OER electrocatalytic performance. This work offers a simple way to build sulfide/alloy heterostructures to improve the electrocatalytic activity of electrocatalysts.

First-principles study of the electronic and catalytic properties of nickel-antimony (Ni-Sb) alloy catalyst for hydrogen evolution reaction

Hydrogen evolution reaction (HER) is a vital half-reaction for water splitting to produce H2. Exploring efficient, affordably priced, and environmentally sustainable HER catalysts is necessary for the development of renewable energy conversion and storage technologies. Here, the HER catalytic activity of hexagonal NiSb(010), hexagonal NiSb(001), hexagonal NiSb(101), cubic Ni3Sb(100), cubic Ni3Sb(010), cubic Ni3Sb(101), orthorhombic Ni3Sb(010), and orthorhombic Ni3Sb(101), is systematically investigated by density functional theory methods. Based on the calculated surface energy, all the studied surfaces are stable. Subsequently, we further evaluate their HER activity by calculating Gibbs free energy of hydrogen adsorption (ΔG*H) and exchange current density (i0). The results show that hexagonal NiSb and orthorhombic Ni3Sb are expected to be promising HER catalysts in Ni-Sb alloys because their ΔG*H values are respectively −0.03 and 0.03 eV, and they have larger i0 values. The synergistic interaction between the metal atoms of Ni and Sb can effectively promote electron transfer between the catalyst and reaction species, which is clearly demonstrated by the electronic structure analysis, which also illustrates that such high catalytic activity can be attributed to it. This work is conducive to guiding the design of this kind of alloy electrocatalysts for HER.

Rapid carbothermal shocking fabrication of iron-incorporated molybdenum oxide with heterogeneous spin states for enhanced overall water/seawater splitting.

Molybdenum dioxide (MoO2) has been considered as a promising hydrogen evolution reaction (HER) electrocatalyst. However, the active sites are mainly located at the edges, resulting in few active sites and poor activity in the HER. Herein, we first reported on an efficient strategy to incorporate Fe into MoO2 nanosheets on Ni foam (Fe-MoO2/NF) using a rapid carbothermal shocking method (820 °C for 127 s). Notably, the different spin states between Fe and Mo atoms could lead to rich lattice dislocations in Fe-MoO2/NF, exposing abundant oxygen vacancies and the low-oxidation-state of Mo sites during the rapid Joule heating process. As tested, the catalyst exhibited superior activity with ultralow overpotentials (HER: 17 mV@10 mA cm-2; oxygen evolution reaction (OER): 310 mV@50 mA cm-2) and high OER selectivity in alkaline seawater splitting. Meanwhile, this catalyst was equipped in a home-made anion exchange membrane (AEM) seawater electrolyzer, which achieved a low energy consumption (5.5 kW h m-3). More importantly, Fe-MoO2/NF also coupled very well with a solar-driven electrolytic system and turned out a solar-to-hydrogen (STH) efficiency of 13.5%. Theoretical results also demonstrated that Fe incorporated and abundant oxygen vacancies in MoO2 can distort the distance of the Mo-O bonds and regulate the electronic structure, thus optimizing the binding energy of H*/OOH* adsorption. This method can be extended to other heterogeneous spin states in MoO2-based catalysts (e.g. Ni-MoO2/NF, Co-MoO2/NF) for seawater splitting, and provide a simple, efficient and universal strategy to prepare highly-efficient MoO2-based electrocatalysts.

Platinum monolayer dispersed on MXenes for electrocatalyzed hydrogen evolution: a first-principles study.

Maximizing platinum's atomic utilization and understanding the anchoring mechanism between platinum moieties and their supports are crucial for the hydrogen evolution reaction (HER). Using density functional theory, we investigate the catalyst of a Pt monolayer on the two-dimensional Mo2TiC2 substrate (PtML/Mo2TiC2) for the reaction. This Pt monolayer shows a Pt(111)-like pattern, with its Pt-Pt bond elongated by about 0.1 Å compared to Pt(111); charge transfer from Mo2TiC2 to the Pt monolayer leads to significant charge accumulation on Pt. This substantial monolayer metal-support interaction optimizes hydrogen adsorption toward optimal HER activity under both constant charge and potential conditions, making PtML/Mo2TiC2 a promising HER catalyst. Detailed studies reveal that the dominant Volmer-Tafel mechanism in the HER occurs on the 1 monolayer hydrogen-covered PtML/Mo2TiC2 surface. The surface Pourbaix diagram identifies this as the stable surface termination under the electrochemical reaction conditions. These findings provide insights into designing stable, efficient, and low platinum-loaded HER catalysts.

Operando XAS Investigation of Bimetallic Iron−Molybdenum Sulfide Electrocatalysts for the Hydrogen Evolution Reaction

Nowadays green hydrogen production has been seen as a key element for the future development and large-scale implementation of fuel cell technology, while electrolyzer technologies represent the most advanced methods for producing pure hydrogen from water. The preparation of efficient, cost-effective, and stable noble-metal-free electrocatalysts for the hydrogen evolution reaction (HER) at the cathode of proton exchange membrane electrolyzers (PEMEL) remains one of the main issues that need to be solved to allow the widespread use of hydrogen as an energy carrier.Molybdenum sulfide (MoSx) is a well-known material showing promising HER catalytic activity, especially in its amorphous state and when doped with other transition metals1. The successful implementation of a bimetallic iron-molybdenum sulfide electrocatalyst for HER into a PEM electrolyzer has been recently reported2. However, the structure of their active sites requires a more elaborate investigation. In this study, we employed operando X-ray absorption spectroscopy to identify potential-induced structural and electronic changes in FeMoSmw bimetallic iron−molybdenum sulfides and MoSmw obtained by a microwave irradiation synthetic approach 2. Extended X-ray absorption fine structure (EXAFS) spectra at Mo and Fe K-edges under operando conditions provided us with accurate structural characterization of the catalytic active sites: while an amorphous MoS3 phase is detected and retained in both MoSmw and FeMoSmw at low potential, a FeS phase is observed at the Fe K-edge, likely explaining the better performance of the bimetallic iron-molybdenum sulfides electrocatalysts compared to iron-free molybdenum sulfides.

Rh-WO3 Electrocatalyst for Hydrogen Evolution Reaction in the Alkaline Seawater Electrolyte

One potential strategy to develop hydrogen evolution electrocatalysts for producing sustainable hydrogen in water electrolysis is creating electrocatalysts with low-cost, high activity, and high stability. Herein, we show that low-loading metal-based tungsten oxide (WO3) can be used as electrocatalysts for the hydrogen evolution reaction (HER) in acid, alkaline, and alkaline seawater electrolytes. Among prepared electrocatalysts, rhodium (Rh)-WO3 exhibits a high HER activity with the values of overpotential of 48, 116, and 98 mV to obtain a current density of 10 mA.cm-2 in acid, alkaline, and alkaline seawater electrolytes, respectively. In addition, the Rh-WO3 electrocatalyst shows high stability during the HER operation for over 60,000s. Besides, the application of Rh-WO3 electrocatalyst as cathode and commercial ruthenium oxide (RuO2) as an anode for overall water splitting show excellent efficiency with only a potential of 1.45 V to a current density of 10 mA.cm-2 in the alkaline-seawater electrolyte. The Rh-WO3//RuO2 cell also exhibits high stability for over 40,000s. The results provide evidence that Rh-WO3 can be a promising HER catalyst for sustainable hydrogen production via alkaline-seawater electrolysis application, as show in Figure 1. Figure 1

Water splitting by CoFeLDH@NiFeS nanoelectrocatalyst assisted urea electrooxidation reaction

In this paper, NiFeS@CoFeLDH nanostructure was synthesized for the first time by electrochemical method in two steps. In the first stage, the first layer of NiFeS was deposited on the nickel foam (NF) substrate, and in the second stage, the second layer of cobalt-iron layered double hydroxide (CoFeLDH)by controlling the electrodeposition condition was deposited on the first. The deposition time and potential were optimized. The optimized NiFeS@CoFeLDH coating on NF has promising hydrogen evolution reaction (HER) activity, which exhibits small overpotentials of − 191.5, and − 304.0, at the current densities of − 10, and − 100 mA. cm−2, respectively. Furthermore, the synthesized NiFeS@CoFeLDH electrocatalyst only needs 358 mV overpotentials to operate at a current density of 10 mA. cm−2 indicating its great performance for the urea oxidation reaction (UOR). The electrode stability was examined at an industrial scale current density of − 100 and 10 mA. cm−2 for HER and UOR respectively, which showed a very stable response for at least 10 h. The results showed that the simultaneous application of NiFeS and CoFeLDH electrocatalysts has a synergistic effect that increases the surface-to-volume ratio and improves the active sites. According to high performance for HER and UOR and also simple, fast, and binder-free synthesis without using expensive materials for preparing the electrocatalyst layer, the proposed electrode can be used as a good candidate for water splitting in the presence of urea.

Acenaphthenediimine complex-bridged porphyrin porous organic polymer with enriched active sites as a robust water splitting electrocatalyst

To realize efficient water splitting, a highly promising hydrogen evolution reaction (HER) electrocatalyst is needed for the generation of hydrogen. Herein, we demonstrate a novel acenaphthenediimine complex-bridged porphyrin porous organic polymer (NiTAPP-NiACQ) with enriched active metal sites and hierarchical pores. The as-prepared NiTAPP-NiACQ exhibits good long-term durability and remarkable HER performance in 1.0 M KOH with a low overpotential of 117 mV at 10 mA cm−2, which is comparable to many previously reported electrocatalytic HER systems. Furthermore, a simple water-alkali electrolyzer using NiTAPP-NiACQ as the cathode requires a small cell voltage of 1.59 V to deliver a current density of 10 mA cm−2 at room temperature, along with outstanding durability. NiTAPP-NiACQ features not only a metal ion as the catalytic active center in the porphyrin core but also metal ion coordination on the anthraquinone component to promote HER performance, enabling multiple metal ions as the electrocatalytic active sites for the HER reaction. The excellent HER activity of NiTAPP-NiACQ is ascribed to a combination of mechanisms. These findings highlight the viability of porphyrin-derived porous organic polymers in energy conversion processes.

Tailoring the Mo-N/Mo-O configuration in MoO2/Mo2N heterostructure for ampere-level current density hydrogen production

Mo-based electrocatalysts have garnered significant attention for their promising hydrogen evolution reaction (HER) efficiency, however, the strong adsorption of hydrogen poses a challenge to speedy gaseous hydrogen release. In this respect, regulating the coordination of Mo atoms is an efficient strategy to optimize the electronic configuration and accelerate the HER kinetics. Herein, MoO2/Mo2N heterostructures are prepared by a programmed in situ nitridation process. The precisely controlled Mo-N/Mo-O configuration in MoO2/Mo2N heterostructure weakens hydrogen adsorption on the Mo sites leading to HER with an ampere-level current density. The electrocatalyst delivers 1 A cm−2 at an overpotential of 335 mV in 0.5 M H2SO4. Furthermore, the electrocatalyst has excellent stability by maintaining a current density of 1 A cm−2 for 180 hours with a remarkable Faradaic efficiency of 99.8%. The results reveal a novel strategy to precisely modulate the electronic configurations of low-cost transition metal-based electrocatalysts boding well for industrial-scale hydrogen production.

The effects of growth environments on WS2 in electrocatalytic hydrogen evolution reaction

Transition metal dichalcogenides (TMDs) recently have attracted much attention because of their outstanding catalytic activity, low cost, and earth abundance in the hydrogen evolution reaction (HER). Among these TMDs, MoS2 and WS2 are recognized as promising HER electrocatalysts and have been explored to be one of the candidates for replacing precious metals. In this work, the electrocatalytic activity of WS2 grown in Ar-only, Ar + H2, and ambient environments were studied, where the WS2 was synthesized by thermolysis from (NH4)2WS4 precursor. Different surface morphologies are shown under the different growth atmospheres. The structures of pure WS2, WS2 and WO3 mixed, and almost WO3 were prepared in different growth atmospheres of Ar-only, Ar + H2, and ambient environment, respectively. All the materials prepared in these different environments exhibit high crystalline characteristic. Especially, the pure WS2 grown in an Ar-only environment presents the preferred (103) lattice plane. The pure WS2 performs the best H2 evolution efficiency, indicating that high crystallinity and preferred (103) lattice plane could be relative to the electrocatalytic activity. The studies provide fundamental insight for further design and preparation of electrocatalysts, useful in the development of clean energy.

Ni2P/MoP encapsulated in N, P-doped carbon nanotubes on carbon cloth for long-lasting electrocatalytic water splitting

The construction of high-performance bifunctional self-supported electrodes is significant for promoting the activity and stability of water splitting. The self-supported electrode not only has a strong structural characterization but also avoids the negative effects of using binders. Herein, we fabricated a self-supported electrode (Ni2P/MoP@CNTs-CC), which is composed of carbon nanotubes (CNTs) directly grown on carbon cloth (CC) filled with transition metal-based phosphide composite nanoparticles. The optimized Ni2P/MoP@CNTs-CC electrode exhibits promising hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) electrocatalytic performance. Ni2P/MoP@CNTs-CC shows a low overpotential of 87 mV at − 10 mA cm−2 and 360 mV at 40 mA cm−2 for HER and OER, respectively. Besides, the Ni2P/MoP@CNTs-CC electrode was also used as an anode and cathode, simultaneously, showing a cell voltage of 1.89 V at 50 mA cm−2 and excellent stability at 50 mA cm−2 for more than 100 h. This work provides a facile method for preparing a low-cost and robust self-supported electrode for water splitting.

Keplerate polyoxomolybdate nanoball mediated controllable preparation of metal-doped molybdenum disulfide for electrocatalytic hydrogen evolution in acidic and alkaline media

Rationally designed novel cost-effective hydrogen evolution reaction (HER) electrocatalysts with controlled surface composition and advanced structural superiority is extremely critical to optimize the HER performance. Polyoxometalates (POMs) with structural diversity and adjustable element compositions represent a promising precursor for rational design and preparation of HER electrocatalysts. Herein, a series of transition metal-doped MoS2 materials with different surface engineered structures (Fe, Cr, V doping and S vacancies) (M-MoS2/CC, M = Fe, Cr and V) were fabricated by a simple hydrothermal-vulcanization strategy using Keplerate polyoxomolybdate nanoball ({Mo72Fe30}, {Mo72Cr30}, {Mo72V30}, {Mo132}) as precursors. The enlarged interlayer spacing as well as the integration of homogeneous transition metal doping and abundant sulfur vacancies endows prepared M-MoS2/CC with superior HER electrocatalytic performance and excellent long-term working stability in both acidic and alkaline media. The optimized Fe-MoS2/CC afford current densities of 10 and 50 mA/cm2 at overpotentials of 188/272 mV and 194/394 mV in 0.5 mol/L H2SO4 and 1.0 mol/L KOH aqueous solution, respectively, outperforming most of reported typical transition metal sulfide-based catalysts. This work represents an important breakthrough for POMs-mediated highly efficient transition metal sulfide-based HER electrocatalysts with wide range pH activity and may provide new options for the rational design of promising HER electrocatalysts and beyond.

Nitrogen-Regulated Nickel d Band Sites in Fullerene-Derived Electrocatalysts Boost the Alkaline Hydrogen Evolution Reaction

Design and construction of efficient and robust electrocatalysts for the hydrogen evolution reaction (HER) are of great importance for renewable energy technologies, but challenge remains for the large-scale commercial application. The good stability and large electrochemical active area of nanomaterials have been widely studied in the field of energy storage and conversion. Regulating the d band electronic structure has been considered as a powerful approach to boost the HER activity. Herein, an efficient electrocatalyst comprising Ni nanoparticles anchored on the N-doped carbon matrix derived from a fullerene/nickel tetraphenylporphyrin (C60/NiTPP) nanoflower assembly was fabricated successfully. The as-synthesized Ni(TPP)/NC exhibited promising HER activity under alkaline condition. To deliver a current density of 10 mA cm–2, it required an overpotential of 114 mV along with a nearly 100% Faradaic efficiency. Both experimental and density functional theory calculation results revealed that the pyrrolic N could modulate the 3d band center of Ni sites in Ni(TPP)/NC, which facilitate the adsorption of water molecules and desorption of hydrogen intermediates, leading to the reduced kinetic energy barrier and enhanced electrocatalytic HER activity. This work would provide useful guidance for designing and developing efficient electrocatalysts for hydrogen production.

High electrocatalytic activity of Rh-WO3 electrocatalyst for hydrogen evolution reaction under the acidic, alkaline, and alkaline-seawater electrolytes

One potential strategy to develop hydrogen evolution electrocatalysts for producing sustainable hydrogen in water electrolysis is creating electrocatalysts with low-cost, high activity, and high stability. Herein, we show that low-loading metal-based tungsten oxide (WO3) can be used as electrocatalysts for the hydrogen evolution reaction (HER) in acid, alkaline, and alkaline-seawater electrolytes. Among prepared electrocatalysts, rhodium (Rh)-WO3 exhibits a high HER activity with the values of overpotential of 48, 116, and 98 mV to obtain a current density of 10 mA cm−2 in acid, alkaline, and alkaline-seawater electrolytes, respectively. In addition, the Rh-WO3 electrocatalyst shows high stability during the HER operation for over 60,000 s. Besides, the application of Rh-WO3 electrocatalyst as cathode and commercial ruthenium oxide (RuO2) as an anode for overall water splitting show excellent efficiency with only a potential of 1.45 V to a current density of 10 mA cm−2 in the alkaline-seawater electrolyte. The Rh-WO3//RuO2 cell also exhibits high stability for over 80,000 s and maintains a current of 15 mA cm2 at a cell voltage of 1.51 V. The results provide evidence that Rh-WO3 can be a promising HER catalyst for sustainable hydrogen production via alkaline-seawater electrolysis application.