Excellent HER Performance Research Articles

Electrochemical behavior of the flower shaped CoMn2O4 spinel structure assembled for effective HER from water splitting

This research focuses on the electrochemical properties of the spinel structure, which is a specific structure of Co-Mn bimetal, and the active species therein, rather than the hydrogen evolution (HER) performance of Co-Mn-based bimetal oxides. The catalysts of four types are prepared by following a solvothermal process and coated on a NiOOH/NF support electrode (NNF). Compared to the CoO and Mn2O3 single particle-assembled electrodes, the CoMn2O4/NNF electrode coated with the flower shaped CoMn2O4 bimetallic particle displays the higher stability in HER. The double-layer capacitance of the CoMn2O4/NNF electrode (25.6 mF cm−2) is approximately three or four times higher than those of the CoO/NNF and Mn2O3/NNF electrodes, meaning that the CoMn2O4/NNF electrode has a larger electrochemical active surface area. The CoMn2O4/NNF electrode additionally has a low overpotential (132 mV), implying that it's HER activity is superior to the other electrocatalysts. It is demonstrated that the structural characteristic of CoMn2O4 contributes to the excellent stability in a long-term HER test. The Density-functional theory (DFT) calculations reveal that the Volmer step is promoted on the (101) crystal plane of CoMn2O4; i.e., the rate of H* formation increases, which causes the HER kinetics to be enhanced. Thus, the experimental and theoretical findings in this study prove the excellent HER performance of CoMn2O4 particles.

Heterogeneous Bimetallic Selenide Anchored Carbon Nanotubes for Boosted Hydrogen Reactions

Herein, bimetallic sulphide CoSe2-FeSe2 anchored on the surface of carbon nanotube (CNT) networks are prepared via a selenization and subsequent annealing process. The CoSe2- FeSe2/CNT hybrid shows excellent property for electrocatalytic hydrogen evolution reaction, featured by a low Tafel slope of 39 mV dec−1, an overpotential of 205 mV (10 mA cm−2), as well as good long-term stability in 0.5M H2SO4 electrolyte. The outstanding HER performance is mainly due to the synergistic effects of the bi-metallization and its unique porous nanoarchitecture: the bi-metallization causes strong coupling interaction between CoSe2 and FeSe2, which facilitates the charge transfer at the interfaces and the reconfiguration of the partial electron structure; the porous nanoarchitecture enable the close contact between electrolyte and active site as well accelerate the evolved gas bubbles releasing. This work provides insight into facile fabrication of bi-metallic selenide electrocatalysts with excellent HER performance in acid medium.

Cyanogroup functionalized sub-2 nm ultrafine Pt nanonetworks reinforce electrocatalytic hydrogen evolution in a broad pH range

Cyanogroup functionalized Pt ultrafine nanonetworks are synthesized via a facile one-pot oil bath heating method, and exhibit excellent HER performance in a broad pH range.

The controlled synthesis of V-doped MoS2-NixSyhollow nanospheres and their electrocatalytic performance in hydrogen evolution reaction

V-doped MoS2-NixSy/NF hollow nanospheres by anin situone-pot method showed excellent HER performance in 1 M KOH solution.

The facile synthesis of core-shell PtCu nanoparticles with superior electrocatalytic activity and stability in the hydrogen evolution reaction.

Pt is the most efficient electrocatalyst for the hydrogen evolution reaction (HER); however, it is a high cost material with scarce resources. In order to balance performance and cost in a Pt-based electrocatalyst, we prepared a series of PtCu bimetallic nanoparticles (NPs) with different Pt/Cu ratios through a facile synthetic strategy to optimize the utilization of Pt atoms. PtCu NPs demonstrate a uniform particle size distribution with exposed (111) facets that are highly active for the HER. A synergetic effect between Pt and Cu leads to electron transfer from Pt to Cu, which is favorable for the desorption of H intermediates. Therefore, the as-synthesized carbon black (CB) supported PtCu catalysts showed enhanced catalytic performance in the HER compared with a commercial Pt/C electrocatalyst. Typically, Pt1Cu3/CB showed excellent HER performance, with only 10 mV (acid) and 17 mV (alkaline) overpotentials required to achieve a current density of 10 mA cm−2. This is because the Pt1Cu3 NPs, with a small average particle size (7.70 ± 0.04 nm) and Pt–Cu core and Pt-rich shell structure, display the highest electrochemically active surface area (24.7 m2 gPt−1) out of the as-synthesized PtCu/CB samples. Furthermore, Pt1Cu3/CB showed good electrocatalytic stability, with current density drops of only 9.3% and 12.8% in acidic solution after 24 h and in alkaline solution after 9 h, respectively. This study may shed new light on the rational design of active and durable hydrogen evolution catalysts with low amounts of Pt.

Fluorine-doping-assisted vacancy engineering for efficient electrocatalyst toward hydrogen production

A novel F-doped Co2P nanomaterial was successfully prepared by a simple one-step electrodeposition method, showing excellent HER performance.

An Mn-doped NiCoP flower-like structure as a highly efficient electrocatalyst for hydrogen evolution reaction in acidic and alkaline solutions with long duration.

The exploration of efficient non-noble metal electrocatalysts for hydrogen evolution reaction has received considerable attention to replace commercial Pt catalyst. It is known that the cooperative coupling of appropriate non-noble metals exhibits excellent HER performance than a single component. Herein, an Mn-doped NiCoP flower-like electrocatalyst with self-assembled nanosheets on a nickel foam is synthesized via successive hydrothermal methods, followed by low temperature phosphidation. The as-synthesized Mn-NiCoP presents extraordinarily high catalytic activity and robust chemical stability towards the hydrogen evolution reaction in both acidic and alkaline electrolytes. Benefiting from the dual modulation of the morphology structure and chemical compositions, Mn-NiCoP/NF achieves a current density of 10 mA cm-2 at a low overpotential of 37 mV for HER in a 0.5 M H2SO4 solution. Moreover, it only requires overpotentials of 67 mV and 142 mV to deliver current densities of 10 mA cm-2 and 50 mA cm-2 in a 1 M KOH solution, respectively. Remarkably, it holds enhanced stability in 1 M KOH, maintaining HER activity for at least 120 h with negligible overpotential decay. The highly efficient and stable Mn-NiCoP electrocatalyst is valuable in applications relevant to energy storage.

Single-phase perovskite oxide with super-exchange induced atomic-scale synergistic active centers enables ultrafast hydrogen evolution

The state-of-the-art active HER catalysts in acid media (e.g., Pt) generally lose considerable catalytic performance in alkaline media mainly due to the additional water dissociation step. To address this issue, synergistic hybrid catalysts are always designed by coupling them with metal (hydro)oxides. However, such hybrid systems usually suffer from long reaction path, high cost and complex preparation methods. Here, we discover a single-phase HER catalyst, SrTi0.7Ru0.3O3-δ (STRO) perovskite oxide highlighted with an unusual super-exchange effect, which exhibits excellent HER performance in alkaline media via atomic-scale synergistic active centers. With insights from first-principles calculations, the intrinsically synergistic interplays between multiple active centers in STRO are uncovered to accurately catalyze different elementary steps of alkaline HER; namely, the Ti sites facilitates nearly-barrierless water dissociation, Ru sites function favorably for OH* desorption, and non-metal oxygen sites (i.e., oxygen vacancies/lattice oxygen) promotes optimal H* adsorption and H2 desorption.

Hydrothermal Synthesis of Polyhedral Nickel Sulfide by Dual Sulfur Source for Highly-Efficient Hydrogen Evolution Catalysis.

Transition metal sulfides are cheap and efficient catalysts for water splitting to produce hydrogen; these compounds have attracted wide attention. Nickel sulfide (NiS2) has been studied in depth because of its simple preparation process, excellent performance and good stability. Here, we propose a modification to the hydrothermal synthesis method for the fabrication of a highly efficient and stable NiS2 electrocatalyst prepared by two different sulfur sources, i.e., sulfur powder and C3H7NaO3S2 (MPS), for application in hydrogen evolution reactions. The obtained NiS2 demonstrated excellent HER performance with an overpotential of 131 mV to drive -10 mA cm−1 in 0.5 M H2SO4 solution with 5mV performance change after 1000 cycles of stability testing. We believe that this discovery will promote the industrial development of nonprecious metal catalysts.

Graphite Carbon Nitride‐Assisted Ruthenium/Reduced Graphene Oxide as High‐Efficiency Electrocatalyst for Hydrogen Evolution Reaction under Alkaline Conditions

AbstractExploring the high activity and stability of HER electrocatalysts in alkaline media is highly desirable. In this paper, a facile hydrothermal method is proposed for synthesizing the Ru decorated graphite carbon nitride/reduced graphene oxide (Ru‐CN‐rGO), which can be used as efficient electrocatalysts in alkaline media. The optimal Ru‐CN‐rGO (Ru: 4.4 wt%) exhibits enhanced electrocatalytic activity than these of Ru/C and Pt/C, which requires a low overpotential (45 mV) to derive a current density of 10 mA cm−2, a small Tafel slope (40.0 mV dec−1) and a large exchange current density (1.13 mA cm−2). More importantly, the obtained Ru‐CN‐rGO exhibits the long‐term stability in alkaline electrolyte. The comparable results reveal that the CN can adjust the electronic structure of Ru, which is beneficial for accelerating the kinetics reaction, resulting in excellent HER performances. This work provides a new strategy for designing the efficient electrocatalyst.

Efficient Tetra-Functional Electrocatalyst with Synergetic Effect of Different Active Sites for Multi-Model Energy Conversion and Storage.

Energy crisis and global warming due to excessive CO2 emissions are the two major challenges of the world. Conversion of CO2 into useful fuels along with rechargeable metal air batteries and water splitting is one way to combat the energy crisis, which is bottlenecked due to the lack of multifunctional electrocatalyst. Herein simple but multifunctional electrocatalyst, which combined CoNi nanoalloy, N-doped carbon nanotubes, and single atomic Ni sites together is reported. The prepared electrocatalyst has shown remarkable performance for CO2RR, ORR, OER, and HER. The practical utilization of the catalyst is mansifested by a dual model metal CO2/air battery and water electrolyzer. An excellent CO2RR with FE of 99% is achieved in 0.5 M KHCO3 medium. The catalyst exhibits more positive onset (0.98 V) and half wave potential (0.86 V) than Pt/C for ORR, extremely low overpotential (η10) of 250 mV for OER, and thus the lowest ORR/OER potential gap of 0.62 V. In alkaline medium, the catalyst also shows excellent HER performance with η10 of 49 mV, resulting in the smallest cell bias of 1.57 V for overall water splitting to date. This work provides a new pathway to design more stellar multifunctional electrocatalyst for sustainable and clean renewable energy technology.

Continuous synthesis of few-layer MoS2 with highly electrocatalytic hydrogen evolution

As one of the most promising alternative fuels, hydrogen is expected with high hopes. The electrolysis of water is regarded as the cleanest and most efficient method of hydrogen production. Molybdenum disulfide (MoS2) is deemed as one of the most promising alternatives HER catalysts owing to its high catalytic activity and low cost. Its continuous production and efficient preparation become the key problems in future industrial production. In this work, we first developed a continuous micro-reaction approach with high heat and mass transfer rates to synthesize few-layer MoS2 nanoplates with abundant active sites. The defective MoS2 ultrathin nanoplates exhibit excellent HER performance with an overpotential of 260 mV at a current density of 10 mA cm−2, small Tafel slope (53.6 mV dec−1) and prominent durability, which are comparable to most reported MoS2 based catalysts. Considering the existence of continuous devices, it's suitable for the synthesis of MoS2 as high-performance electrocatalysts for the industrial water electrolysis. The novel preparation method may open up a new way to synthesize all two-dimension materials toward HER.

Construction of hierarchical Prussian Blue Analogue phosphide anchored on Ni2P@MoOx nanosheet spheres for efficient overall water splitting

In response to the energy crisis, molybdenum-based catalyst has been proposed as a high-performance electrocatalytic material due to its low price and excellent HER performance. However, in contrast with its excellent HER performance, its poor OER performance often limits practical application as a high-performance overall water splitting catalyst. In this study, Prussian blue analogue (PBA) is grown in-situ on molybdenum-based nanosheet spheres by a simple and ingenious method and then subjected to phosphorization. The resulting composite catalyst exhibits highly efficient overall water splitting performance, overpotentials at current densities of 10 mA cm−2 and 100 mA cm−2 for the HER and OER are −61 mV and 268 mV, respectively. Moreover, an alkaline electrolyzer makes up by the catalyst both as positive and negative can reach a cell voltage 1.494 V at 10 mA cm−2 for the overall water splitting. This method has provided a new strategy to effective combine PBA and molybdenum-based catalyst.

Facile fabrication of hierarchical Rh2Ir alloy nanodendrites with excellent HER performance in a broad pH range

Hierarchical Rh2Ir alloy nanodendrites were prepared via a facile oil-bath method, which exhibits excellent HER performance in a broad pH range.

Confined growth of pyridinic N–Mo2C sites on MXenes for hydrogen evolution

A hybrid of N-doped carbon encapsulated ultrasmall Mo2C nanodots on Ti3C2TxMXene exhibits excellent HER performance in the entire pH range.

Boosting hydrogen evolution performance by using a plasma-sputtered porous monolithic W2C@WC1−x/Mo film electrocatalyst

A sputtering strategy is reported to prepare a porous W2C@WC1−xfilm on carbon cloth in a W, C and Ar ion plasma atmosphere. It exhibits excellent HER performance with a low overpotential (58 mVvs.RHE, −10 mA cm−2current density) and Tafel slope of 41 mV dec−1.

Highly-dispersed ruthenium precursors via a self-assembly-assisted synthesis of uniform ruthenium nanoparticles for superior hydrogen evolution reaction.

For the first time, highly-dispersed ruthenium precursors via a hydrogen-bond-driven melamine–cyanuric acid supramolecular complex (denoted CAM) self-assembly-assisted synthesis of uniform ruthenium nanoparticles with superior HER performance under both acidic and alkaline conditions are reported. Electrochemical tests reveal that when the current density is −10 mA cm−2, the optimal Ru/CNO electrocatalyst could express low overpotentials of −18 mV and −46 mV, low Tafel slopes of 46 mV dec−1 and 100 mV dec−1, in 0.5 M H2SO4 and 1.0 M KOH, respectively. The remarkable HER performance could be attributed to uniform ruthenium with the aid of highly dispersed ruthenium precursors (Ru–CAM) and subsequent annealing results in uniform ruthenium nanoparticles.

Three-dimensional NiCoP hollow spheres: an efficient electrode material for hydrogen evolution reaction and supercapacitor applications.

A binary metal phosphide (NiCoP) has been synthesized in a single-step hydrothermal method, and its energy conversion (hydrogen evolution reaction; HER) and energy storage (supercapacitor) performances have been explored. The physicochemical characterization of the NiCoP nanostructures show that they have a highly crystalline phase and are formed uniformly with a sphere-like surface morphology. In acidic electrolytic conditions, the NiCoP shows excellent HER performance, requiring only 160 and 300 mV overpotential to deliver 10 and 300 mA cm−2 current density, respectively. Interestingly, it follows the Volmer–Heyrovsky reaction pathway to execute the HER with robust durability (∼15 mV increase in overpotential even after 18 h of electrolysis). In an alkaline medium (5 M KOH), NiCoP shows specific capacitance of 960 F g−1 with higher energy density (33.3 W h kg−1) and power density (11.8 kW kg−1). Moreover, it shows better reversibility (∼97% coulombic efficiency) and long cycle life (∼95% capacitance retention after 10 000 repeated cycles). The unique surface morphology and phase purity of the binary metal phosphide avails more electroactive surface/redox centers, thereby showing better electrocatalytic as well as energy storage performances. Therefore, we presume that the NiCoP would be a suitable material for future energy conversion and storage systems.

Interface engineering of Ag-Ni3S2 heterostructures toward efficient alkaline hydrogen evolution.

Exploring Earth-abundant transition-metal-based electrocatalysts with high performance toward the alkaline hydrogen evolution reaction (HER) is crucial for sustainable hydrogen production. Ni3S2 has been recently identified as a promising HER catalyst, but it has unfavorable water dissociation and hydrogen adsorption characteristics. Here, we report Ag-decorated Ni3S2 nanosheet arrays grown on Ni Foam (NF) (Ag-Ni3S2/NF) as efficient heterostructure electrocatalysts for the HER in alkaline media. The catalyst only requires a low overpotential of 89 mV at 10 mA cm-2, as well as sustaining long-term durability for 15 h. The experimental analysis, in combination with density functional theory calculation, demonstrates that the electronic coupling at the interface between Ni3S2 and Ag results in enhanced electronic conductivity and optimized hydrogen adsorption and water adsorption/dissociation free energies. This work not only develops a highly efficient catalyst toward the HER, but also sheds light on the structure-activity relationship of the heterostructure catalyst on an atomic scale.

Ru nanoparticles encapsulated in ZIFs-derived porous N-doped hierarchical carbon nanofibers for enhanced hydrogen evolution reaction

Ru nanoparticles, encapsulated in ZIFs-derived porous N-doped hierarchical carbon nanofibers with excellent HER performance, were achieved.