High-performance Hydrogen Evolution Reaction Research Articles

Tuning of electrocatalytic activity of WO3–TiO2 nanocomposite electrode for alkaline hydrogen evolution reaction

The study reports the synthesis of mesoporous WO3–TiO2 nanocomposite with tuned particle size (~7 nm), pore diameter (~4.9 nm), specific surface area (SBET = 129.112 m2/g) and pore volume (Vtot = 0.185 cm3/g) by an acid catalyzed peptization method, and its utilization for the development of stable catalytic electrode with enhanced activity towards alkaline hydrogen evolution reaction (HER). The SEM and AFM analyses confirm the formation of good quality composite electrodes with improved surface roughness through electroless deposition method. The developed WO3–TiO2 nanocomposite electrode exhibits low overpotential value of 120 mV with an exchange current density of 6.20 × 10−5 mA/cm2, and a low Tafel slope value of 98 mV/dec. Apart from the high HER performance, the developed WO3–TiO2 nanocomposite electrode exhibits competency with the state-of-the-art electrode materials for alkaline HER in industrial processes with sustained catalytic activity, tolerance behavior and long-term stability.

Elimination of Interlayer Potential Barriers of Chromium Sulfide by Self-Intercalation for Enhanced Hydrogen Evolution Reaction.

The van der Waals (vdW) gaps in layered transition-metal dichalcogenides (TMDs) with an interlayer poor charge transport are considered the bottleneck for higher hydrogen evolution reaction (HER) performance of TMDs. Filling the vdW gap of TMDs materials with intercalants is considered a good way to generate new interesting properties. However, postsynthesis intercalation with foreign atoms may bring extra crystalline imperfections and low yields. In this work, to overcome the interlayer potential barriers of TMDs, CrS2-Cr1/3-CrS2 is produced by naturally self-intercalating native Cr1/3 atom plane into the vdW layered CrS2. The CrS2-Cr1/3-CrS2 exhibits strong chemical bonds and high electrical conductivity, which can provide excellent HER electrocatalytic performance. Moreover, based on the first-principles calculations and experimental verification, the intercalated Cr atoms exhibit a Gibbs free energy of the adsorbed hydrogen close to zero and could further improve the electrocatalytic HER performance. Our work provides a new view in self-intercalation for electrocatalysis applications.

VSe2 quantum dots with high-density active edges for flexible efficient hydrogen evolution reaction

Two-dimensional (2D) metallic transition metal dichalcogenides (TMDCs) with large specific surface areas and high conductivities are promising catalysts for electrocatalytic hydrogen production. The highly active edges of the 2D metallic TMDCs are the desirable catalytic sites for the hydrogen evolution reaction (HER). Herein, the vanadium diselenide (VSe2) quantum dots with high-density edge sites are prepared by tip sonication of the self-detached VSe2 nanosheets. The spontaneously released VSe2 nanosheets, without chemical-involved transfer, offer a noncontaminated catalyst for HER. Compared to the VSe2 nanosheets, VSe2 quantum dots with a high density of active edges present a significant enhancement of the electrocatalytic performance. The reduced overpotential and transfer resistance indicate the lower Gibbs free energy and faster faradic process of the VSe2 quantum dots for HER. The active edge sites of VSe2 quantum dots show improved catalytic properties in thermodynamic and kinetic aspects. The VSe2 quantum dots loaded on a carbon cloth could be used as a flexible electrode for HER. This work provides an effective way to regulate the defects of the 2D TMDCs for high-performance HER catalysts and also offers a catalyst for flexible HER.

Identifying Metallic Transition-Metal Dichalcogenides for Hydrogen Evolution through Multilevel High-Throughput Calculations and Machine Learning.

High-performance electrocatalysts not only exhibit high catalytic activity but also have sufficient thermodynamic stability and electronic conductivity. Although metallic 1T-phase MoS2 and WS2 have been successfully identified to have high activity for hydrogen evolution reaction, designing more extensive metallic transition-metal dichalcogenides (TMDs) faces a large challenge because of the lack of a full understanding of electronic and composition attributes related to catalytic activity. In this work, we carried out systematic high-throughput calculation screening for all possible existing two-dimensional TMD (2D-TMD) materials to obtain high-performance hydrogen evolution reaction (HER) electrocatalysts by using a few important criteria, such as zero band gap, highest thermodynamic stability among available phases, low vacancy formation energy, and approximately zero hydrogen adsorption energy. A series of materials-perfect monolayer VS2 and NiS2, transition-metal ion vacancy (TM-vacancy) ZrTe2 and PdTe2, chalcogenide ion vacancy (X-vacancy) MnS2, CrSe2, TiTe2, and VSe2-have been identified to have catalytic activity comparable with that of Pt(111). More importantly, electronic structural analysis indicates active electrons induced by defects are mostly delocalized in the nearest-neighbor and next-nearest neighbor range, rather than a single-atom active site. Combined with the machine learning method, the HER-catalytic activity of metallic phase 2D-TMD materials can be described quantitatively with local electronegativity (0.195·LEf + 0.205·LEs) and valence electron number (Vtmx), where the descriptor is ΔGH* = 0.093 - (0.195·LEf + 0.205·LEs) - 0.15·Vtmx.

Enhanced catalytic hydrogen evolution reaction performance of highly dispersed Ni2P nanoparticles supported by P-doped porous carbon

The development of high-performance and non-noble metal hydrogen evolution reaction (HER) electrocatalysts is significant for industrial hydrogen production. Herein, we developed a facile hydrothermal synthesis of HER electrocatalyst (Ni2P/PC) of three-dimensional (3D) P-doped porous carbon (PC) supported Ni2P nanoparticles (Ni2P NPs). Ni2P/PC composites demonstrated a 3D lamellar porous structure with a large specific surface area (203.8 m2 g−1) and small particle size (15−20 nm) of Ni2P NPs. Furthermore, PC substrate was able to change the binding energy of Ni-P by adjusting the electron density of Ni2P. The Ni2P/PC catalyst exhibited excellent electrocatalytic activity with an impressively low overpotential of 96 mV at a current density of 10 mA cm-2 and a small Tafel slope of 67.01 mV dec−1 in HER. In addition, the electrocatalytic activity showed no obvious attenuation after 2000 cycles. P-doped porous carbon was proven as an ideal support for highly dispersed Ni2P NPs. This study paves the way for the development of highly efficient hybrid HER electrocatalysts.

Heterostructures of MXenes and CoNx-Graphene as highly active electrocatalysts for hydrogen evolution reaction in alkaline media

Hydrogen evolution reaction (HER) plays a vital role in renewable energy conversion for the development of hydrogen-based energy sources. Lately, heterostructures through hybridizing MXenes with two-dimensional materials have been successfully fabricated and attract much attention due to the exceptional performance as electrodes for Li ion storage and electrocatalysts for HER. Herein, we constructed heterostructures of CoNx-graphene (CoNx-G, x = 2 and 4) supported by MXenes (Ti3C2F2 and Ti3C2O2) monolayer as highly active electrocatalysts for HER. The theoretical results show that the CoN2-G/Ti3C2O2 heterostructure exhibits a high performance for HER with an over-potential (Ƞ) of only 0.33 V, and the rate-limiting step is determined to be the initial water dissociation process in alkaline media. The outstanding performance of CoN2-G/Ti3C2O2 is strongly attributed to the interfacial coupling between CoN2-G and the MXene substrate. Our finding demonstrates that the sluggish hydrogen evolution process in alkaline media can be facilitated by taking advantage of the fast charge transfer kinetics and interfacial coupling of MXenes. Herein, we theoretically design and explore 2D hybrid materials of CoNx–G supported by MXene monolayers as highly active HER electrocatalysts by using first-principles calculations. The results show that the CoN2–G/Ti3C2O2 heterostructure has an outstanding HER performance with ΔGH* (0.21 eV) approaching zero as well as water molecule dissociation barrier (ΔGH–OH) of 0.30 eV in alkaline media. This exceptional performance is strongly attributed to the interfacial coupling between CoN2–G and the MXene substrate.

New Insight of Pyrrole-Like Nitrogen for Boosting Hydrogen Evolution Activity and Stability of Pt Single Atoms.

Single atomic Pt catalysts exhibit particularly high hydrogen evolution reaction (HER) activity compared to conventional nanomaterial-based catalysts. However, the enhanced mechanisms between Pt and their coordination environment are not understood in detail. Hence, a systematic study examining the different types of N in the support is essential to clearly demonstrate the relationship between Pt single atoms and N-doped support. Herein, three types of carbon nanotubes with varying types of N (pyridine-like N, pyrrole-like N, and quaternary N) are used as carbon support for Pt single atom atomic layer deposition. The detailed coordination environment of the Pt single atom catalyst is carefully studied by electron microscope and X-ray absorption spectra (XAS). Interestingly, with the increase of pyrrole-like N in the CNT support, the HER activity of the Pt catalyst also improves. First principle calculations results indicate that the interaction between the dyz and s orbitals of H and sp3 hybrid orbital of N should be the origin of the superior HER performance of these Pt single atom catalysts (SACs).

Surface Modifications of 2D-Ti3C2O2 by Nonmetal Doping for Obtaining High Hydrogen Evolution Reaction Activity: A Computational Approach

As a typical two-dimensional (2D) MXene, Ti3C2O2 has been considered as a potential material for high-performance hydrogen evolution reaction (HER) catalyst, due to its anticorrosion and hydrophilic surface. However, it is still a challenge to improve the Ti3C2O2 surficial HER catalytic activity. In this work, we investigated the HER activity of Ti3C2O2 after the surface was doped with S, Se, and Te by the first principles method. The results indicated that the HER activity of Ti3C2O2 is improved after being doped with S, Se, Te because the Gibbs free energy of hydrogen adsorption (ΔGH) is increased from −2.19 eV to 0.08 eV. Furthermore, we also found that the ΔGH of Ti3C2O2 increased from 0.182 eV to 0.08 eV with the doping concentration varied from 5.5% to 16.7%. The HER catalytic activity improvement of Ti3C2O2 is attributed to the local crystal structure distortion in catalytic active sites and Fermi level shift leads to the p-d orbital hybridization. Our results pave a new avenue for preparing a low-cost and high performance HER catalyst.

Transition-Metal Carbides as Hydrogen Evolution Reduction Electrocatalysts: Synthetic Methods and Optimization Strategies.

With the strengths of zero carbon emission and high gravimetric energy density, hydrogen energy is recognized as a primary choice for future energy supply. Electrochemical water splitting provides a promising strategy for effective and sustainable hydrogen production through renewable electricity, and one of the immediate challenges toward its large-scale application is the availability of low-cost and efficient electrocatalysts for the hydrogen evolution reaction (HER). Given the enormous efforts in the exploration of potential transition-metal carbide (TMC) electrocatalysts, this review aims to summarize the recent advances in synthetic methods and optimization strategies of TMC electrocatalysts. Additionally, the perspectives for the development of novel efficient TMC-based catalysts are also proposed.

A NiCoP nanocluster-anchored porous Ti3C2Tx monolayer as high performance hydrogen evolution reaction electrocatalysts.

MXenes have received much attention as promising candidates for noble metal-free hydrogen evolution reaction (HER) electrocatalysts due to their high electrical conductivity, surface hydrophilicity, abundant surface functional groups, and great potential for rational hybridization with other materials. Herein, a novel porous monolayered-Ti3C2Tx@NiCoP (P-Ti3C2Tx@NiCoP) nanostructure was synthesized with uniform distribution of bimetallic compounds for improved charge transfer capability and electrocatalytic activity. In experiments, H2O2-utilized oxidation formed a highly mesoporous structure with a maximized surface area of monolayered MXenes as the support. A subsequent solvothermal process followed by phosphidation enabled successful anchoring of highly HER-active NiCoP nanoclusters onto abundantly exposed terminal edges of the P-Ti3C2Tx support. The structural porosity of the P-Ti3C2Tx nanoflakes played an important role in creating additional room for embedding catalytically active species while stably imparting high electrical conductivity to accelerate charge transfer to NiCoP nanoclusters. With structural modification and effective hybridization, P-Ti3C2Tx@NiCoP showed highly enhanced HER activity with significantly lower overpotentials of 115 and 101 mV at a current density of -10 mA cm-2 in 0.5 M H2SO4 and 1.0 M KOH, respectively, along with showing long-term stability over 60 h. As such, our approach of designing structurally modified-Ti3C2Tx and hybridizing with other electrocatalytically active species would function as a solid platform for implementing Ti3C2Tx-based hetero-nanostructures to achieve state-of-the-art performance in next-generation energy conversion applications.

Cobalt disulfide supported on porous carbon foam as a high performance hydrogen evolution reaction catalyst

An excellent cobalt disulfide–carbon foam composite catalyst was synthesized by a hydrothermal method for the electrochemical hydrogen evolution reaction (HER).

Doping and strain effect on hydrogen evolution reaction catalysts of NiP<sub>2</sub>

Hydrogen production through electrolyzing water can transfer the energy from solar energy, wind energy and other sustainable energy to hydrogen, a clean energy carrier with high energy density. The NiP<sub>2</sub> has attracted much attention as a cheap electrocatalyst with high catalytic performance for hydrogen evolution reaction (HER). In this paper, the adsorption energy, Gibbs free energy and exchange current densities at different sites on NiP<sub>2</sub> (100) surface are calculated. On this basis, the effect of strain and doping on the HER catalytic performance of NiP<sub>2</sub> are studied. By calculation, we find that when H is adsorbed on the top site of P atom on NiP<sub>2</sub> (100) surface, the exchange current density is the closest to the top of volcanic curve, so the top site of P atom on NiP<sub>2</sub> (100) surface is the catalytic active site. The effect of doping and strain on the catalytic performance of NiP<sub>2</sub> are analyzed. 1) According to the range of strain produced by the common experimental technology, the effects of 1% and 3% tensile and compressive strain are calculated. It is found that 1% compressive strain can improve the catalytic performance of NiP<sub>2</sub>, while when 3% compressive strain or a 1% or 3% tensile strain is applied, the catalytic performance of NiP<sub>2</sub> is not enhanced. 2) The effects of doping transition metal elements (Co, Fe, Mn, Mo, Cu, W, Cr) and non-metallic elements (N, C, S) on the catalytic performance of NiP<sub>2</sub> are calculated. It is found that doping non-metallic element S can significantly improve the HER catalytic performance of the top site of P atom, while the doping of transition metal elements Mn, Mo, W, Co, Cr, Fe, Cu and non-metallic elements N, C have no effect on this site. The doping of transition metal element (catalytic activity: Mn > Mo > W > Co > Cr > Fe > Ni) Mn can make the catalytic performance of inactive site improved to that of the active site, thus indirectly improving the catalytic performance of NiP<sub>2</sub>. Our work reveals the micro mechanism of the effect of doping and strain on the performance of HER electrocatalyst, which provides a new perspective for designing the high performance HER electrocatalyst.

Acetylenic bond-driven efficient hydrogen production of a graphdiyne based catalyst

3D acetylenic bonds distributing makes tetraphenyl methane substitute graphdiyne (TPM-GDY) show more active sites and high hydrogen evolution reaction performance.

Engineered MoSe2/WSe2 based heterostructures for efficient hydrogen evolution reaction

Electrocatalytic water splitting into hydrogen and oxygen using semiconducting heterogeneous nanostructures is a promising and emerging technology. Semiconductor materials based heterogeneous nanostructures have attracted much attention to be used as catalysts, co-catalysts, photocatalysts and photo absorbers. The present work deals with the investigation of heterostructures of molybdenum selenide (MoSe2) and tungsten selenide (WSe2) nanosheets prepared through liquid exfoliation method as electrocatalysts for the hydrogen evolution reaction (HER). Our experimental studies reveal that MoSe2/WSe2 heterostructures synthesized using hydrogen peroxide (H2O2) exhibits superior HER performance. These novel structures leads to the exposure of more catalytically active sites and maintains effective electron transport, resulting in a small Tafel slope of 80 mV/decay and large electrochemical surface area (ECSA) of 87. This low-cost method finds application in high-performance HER electrocatalyst.

In-situ generation of Ru-catechol coordinative polymer precursor for high-performance hydrogen evolution reaction doped carbon catalyst

We report a coordinative strategy to introduce ruthenium (Ru) into nitrogen, boron co-doped carbon nanomaterials (Ru-NBCs) thus achieving high hydrogen evolution reaction (HER) activity in both alkaline and acidic conditions. Starting from boronate polymer nanospheres prepared by a condensation reaction between catechol and boronic monomers, a Ru3+-catechol coordination reaction can easily produce metallosupramolecular polymer precursors. Ru-NBCs derived from the sintering of these precursors exhibit excellent HER properties with lowest overpotentials of 14 mV in 1.0 M KOH and 22 mV in 0.5 M H2SO4 at a current density of 10 mA/cm2. The mass activity of Ru-NBCs is much higher than that of commercial Pt/C. Meanwhile, the active site density and turnover frequency (TOF) value of Ru-NBCs are studied. This strategy has high adaptability to various catechol and boronic building blocks with different structures, thus showing promising application in the design of high performance metal-incorporated doped carbon materials.

Polypyrrole Hollow Microspheres with Boosted Hydrophilic Properties for Enhanced Hydrogen Evolution Water Dissociation Kinetics

The water dissociation step (H2O + M + e- → M - Hads + OH-) is a crucial one toward achieving high-performance hydrogen evolution reaction (HER). The application of electronic conducting polymers (ECPs), such as polypyrrole (PPy), as the electrocatalyst for HER is rarely reported because of their poor adsorption energy per water molecule, which hinders the Volmer step. Herein, we strongly enrich PPy hollow microspheres (PPy-HMS) with attractive HER activity by enhancing their hydrophilic properties through hybridization with good water affinity SiO2. The as-prepared PPy-coated SiO2 (PPy@SiO2-HMS) achieves a current density of 10 mA cm-2 at -123 mV, which is lower than that of pristine PPy-HMS (-192 mV). Raman and X-ray photospectroscopy analyses reveal that the enhanced HER catalytic capability can be attributed to the strong electronic couplings between PPy and SiO2, and this improves the adsorption energy per water molecule and in turn accelerates the water dissociation kinetics on PPy. This work highlights the potential application of low-cost ECPs as promising electrocatalysts for water electrolysis.

Design of 2D Layered Catalyst by Coherent Heteroepitaxial Conversion for Robust Hydrogen Generation

AbstractThe structural engineering of 2D layered materials is emerging as a powerful strategy to design catalysts for high‐performance hydrogen evolution reaction (HER). However, the ultimate test of this technology under typical operating settings lies in the reduced performance and the shortened lifespan of these catalysts. Here, a novel approach is proposed to design efficient and robust HER catalysts through out‐of‐plane deformation of 2D heterojunction using metal‐organic chemical vapor deposition. High‐yield, single‐crystalline WTe2 nanobelts are used as an epitaxial template for their coherent conversion to WS2. During the conversion process, the WTe2/WS2 heterostructure containing both lateral and vertical junctions are achieved by coherent heteroepitaxial stacking despite differences in symmetry. The lattice coherency drives out‐of‐plane deformation of heteroepitaxially grown WS2. The increase in the effective surface area and decrease in the electron‐transfer resistance across the 2D heterojunctions in turn enhances the HER performance as well as the long‐term durability of these electrocatalysts.

Synergistic two- and three-dimensional morphology engineering of pyrite-type CoPS to boost hydrogen evolution over wide pH range

By designing the morphology and architecture of employed electrocatalysts, the development of high-performance hydrogen evolution reaction (HER) electrocatalysts for electrolytes with a wide pH range is practical significance for future energy conversion technologies. Herein, we synthesize an electrocatalyst composing of two-dimensional (2D) ultrathin ternary pyrite-type cobalt phosphosulfide nanosheets and conductive carbon black (CoPS NSs/C) by the one-step phosphosulfide process. Thanks to the introduction of the C, the composite not only presents a unique three-dimensional (3D) interconnected reticulum structure but also effectively reduces the thickness of nanosheets. The as-synthesized electrocatalyst exhibits remarkable small overpotential toward HER in wide pH range. Meanwhile, the electrocatalyst owns higher charge transfer rate and excellent stability. The good performance is mainly attributed to the combination of the advantages of both 2D nanosheets and 3D interconnected reticulum structure, which offers larger surface area, sufficient active sites and more contaction with electrolytes. This work provides a new method for preparing ultrathin ternary transition-metal phosphosulfide (TMPS) nanosheets, and offers a facile route for improving electrocatalytic activity by designing synergistic morphology of 2D and 3D.

Interfacial Engineering of a MoO2-CeF3 Heterostructure as a High-Performance Hydrogen Evolution Reaction Catalyst in Both Alkaline and Acidic Solutions.

Exploring an efficient and pollution-free hydrogen evolution reaction (HER) electrocatalyst based on the combination of rare-earth metal and nonnoble metal is of significant importance. However, successfully achieving such a goal remains highly challenging. Herein, a nanosheet comprising a MoO2-CeF3 heterojunction (MoO2-CeF3/NF) is successfully prepared via a three-step method. (1) Growth of hexahedral nickel hydroxide [Ni(OH)2] on a 3D nickel foam (NF) as the scaffold. (2) In situ hydrothermal growth of a precursor nanosheet structure on the scaffold. (3) Calcination treatment at 450 °C in the presence of hydrogen. Herein, the electron redistribution at the heterointerface of CeF3 and MoO2 is a contributing factor toward enhanced HER activity. Appropriate introduction of CeF3 can enlarge the size of nanosheets, increase numerous active sites, increase the catalytic durability of the material, and change electron distribution on the MoO2 interface; all of the above improve HER activity. Because of its interfacial nanosheet structure, MoO2-CeF3/NF demonstrates pre-eminent HER capability in both alkaline (1.0 M KOH) and acidic (0.5 M H2SO4) electrolytes, with extremely small overpotentials of 18 and 42 mV at 10 mA cm-2, respectively. This is obviously lower than the overpotential of Pt/C in alkaline media (27 mV), and it is also close to the overpotential of Pt/C in acidic media (41 mV), at the same current density. More importantly, MoO2-CeF3/NF displays a better HER activity than Pt/C at a current density of >112 mA cm-2 in both alkaline and acidic electrolytes. This work offers a novel strategy toward high-performance hydrogen production by designing a transition metal oxide and rare-earth metal heterojunction.

High-Performance and Stable Hydrogen Evolution Reaction Achieved by Pt Trimer Decoration on Ultralow-Metal Loading Bimetallic PtPd Nanocatalysts

Hydrogen evolution reaction (HER) plays a key role in combating an ever-growing imbalance and adverse climatic issues. Thus far, Pt-based catalysts are treated as “the Holy Grail” for HER and none ...