An efficient hydrogen evolution catalyst constructed using Pt-modified Ni3S2/MoS2 with optimized kinetics across the full pH range

Electrocatalyst materials play a crucial role in determining the efficiency of the hydrogen evolution reaction (HER), directly influencing the overall effectiveness of energy conversion technologies. Ni3S2/MoS2 heterostructures hold substantial promise as bifunctional catalysts, owing to their synergistic electronic characteristics and plentiful active sites. However, their catalytic efficacy is impeded by the relatively elevated chemisorption energy of hydrogen-containing intermediates, which constrains their functionality in different pH environments. In order to mitigate this limitation, trace amounts of Pt are introduced into the heterostructure, intending to enhance electronic transport and refining chemisorption energies, thereby facilitating significant enhancements in both HER and oxygen evolution reaction (OER) activities over a wide pH range. It is revealed that the Pt-modified catalyst achieves exceptional HER performance, requiring merely 64 mV and 83 mV overpotentials to attain a current density of 100 mA cm-2 in acidic and alkaline media, respectively. Furthermore, theoretical simulations corroborate that Pt modification optimizes local electronic configurations and augments electronic transfer, contributing to its superior catalytic performance. This investigation underscores the pivotal role of Pt modification in propelling the practical application of Ni3S2/MoS2 heterostructures as highly efficient and pH-universal bifunctional catalysts.

Fabrication of Trimetallic Fe-Co-Ni Electrocatalysts for Highly Efficient Oxygen Evolution Reaction

The development of inexpensive and well-activated water-splitting catalysts is required to reduce the use of conventional fossil fuels. In this study, a trimetallic Fe-Co-Ni catalyst was fabricated using a simple ion electrodeposition method. The metal deposition was performed using cyclic voltammetry, which was more efficient than constant-voltage deposition and significantly increased the stability of the catalyst. The synthesized material presented the morphology of a nanoflower in which the nanosheets were agglomerated. The Fe-Co-Ni catalyst exhibited excellent oxygen evolution reaction (OER) properties because the charge-transfer rate was improved owing to the synergistic effect of the metals. The OER was performed in a 1 M KOH solution using a three-electrode system, and the overpotential was 302 mV at 100 mA/cm². In addition, the Fe-Co-Ni catalyst exhibited excellent stability in alkaline solution for more than 48 h at 200 mA/cm². The results show that the method for preparing Fe-Co-Ni significantly improves its catalytic activity, and the resulting material could be used as an economical and efficient catalyst in future.

Synergistic catalysis of graphitic carbon nitride supported bimetallic sulfide nanostructures for efficient oxygen generation

Herein, a series of g-C₃N₄ supported bimetallic sulfide nanostructures (Ni₃S₂/MoS₂/ng-C₃N₄, n = 10, 20 and 30) was prepared by a hydrothermal method and subsequently a thermal annealing approach. Ni₃S₂/MoS₂/20g-C₃N₄ with controlled composition exhibits efficient OER activity with a low overpotential of 183 mV at 10 mA cm^-2, which outperforms the vast majority of sulfide OER electrocatalysts reported previously.

Fluorine-anion engineering endows superior bifunctional activity of nickel sulfide/phosphide heterostructure for overall water splitting

Designing advanced transition metal-based materials for electrocatalytic water splitting is of significance, but their wide application is still limited due to the lack of an effective regulation strategy. Herein, a synergistic regulation strategy of surface/interface is developed to optimize the catalytic activity of nickel sulfide (Ni₃S₂). The construction of nickel phosphide with Ni₃S₂ heterostructure by using fluorine (F)-anion modification is successfully developed on nickel foam (F-NiP_x/Ni₃S₂-NF) via a simple fluorination and phosphating treatment. This new kind of electrocatalyst contains plenty of active sites and strong electronic interactions, presenting superior bifunctional activity for both hydrogen evolution reaction (HER) and oxygen evolution reaction (OER). The overpotentials only need 182 mV and 370 mV to reach the current density of 100 mA cm^-2 for HER and OER, respectively. In addition, the F-NiP_x/Ni₃S₂-NF-based electrolyzer delivers promising performance for overall water splitting. A low potential of 1.55 V and 1.7 V can be achieved at the current density of 10 mA cm^-2 and 50 mA cm^-2. This work provides a new surface/interface regulation strategy for high-efficient bifunctional electrocatalysts.

Construction of reduced graphene oxide coupled with CoSe2-MoSe2 heterostructure for enhanced electrocatalytic hydrogen production

It is important to develop novel energy to solve energy shortage and environmental problems. Hydrogen evolution reaction (HER) is envisaged as a viable technology that can be used to develop sustainable clean energy. Herein, we report a catalyst with CoSe₂-MoSe₂ heterostructure grown on reduced graphene oxide with an optimum Co/Mo proportion of 1:1 (CoSe₂-MoSe₂(1-1)/rGO). It exhibits good HER activities in both acidic and alkaline conditions. The CoSe₂-MoSe₂(1-1)/rGO shows an overpotential of 107 mV at 10 mA cm^-2 with a Tafel slope of 56 mV dec^-1 under acidic condition. Meanwhile, CoSe₂-MoSe₂(1-1)/rGO also presents an overpotential of 182 mV at 10 mA cm^-2 and with a Tafel slope of 89 mV dec^-1 under alkaline condition. These impressive performances of the catalyst are mainly due to the excellent electronic transmission capability of rGO and the abundant active sites of CoSe₂-MoSe₂ heterostructure as well as the optimized hydrogen adsorption energy of CoSe₂-MoSe₂ interface. The design of CoSe₂-MoSe₂(1-1)/rGO provides a meaningful guide for manufacturing electrode in energy storage and conversion.

Ru@Ni3S2 nanorod arrays as highly efficient electrocatalysts for the alkaline hydrogen evolution reaction

Ru-decorated Ni3S2 nanorod arrays demonstrate an superior alkaline hydrogen evolution performance. Further modification with polyaniline could significantly enhance the long-term stability for continuous hydrogen generation.

Self-supported Ni3S2@Ni2P/MoS2 heterostructures on nickel foam for an outstanding oxygen evolution reaction and efficient overall water splitting

Hydrogen production by electrocatalytic water splitting is a pollution-free, energy-saving, and efficient method. The low efficiency of hydrogen production, high overpotentials and expensive noble-metal catalysts have limited the development of hydrogen production from electrocatalytic water splitting. Therefore, the exploration of bifunctional electrocatalysts for water overall splitting to produce hydrogen is of profound significance. Herein, Ni₃S₂@Ni₂P/MoS₂ heterostructure electrocatalysts were synthesized on Ni foam through an environmentally friendly hydrothermal method and low-temperature phosphating method. The synergistic effects between different components and the mutual substitution principle between sulfur atoms and phosphorus atoms greatly improve the OER performance of the electrocatalyst. It is also an effective strategy to optimize the adsorption energies of intermediates by the design of heterostructured catalysts composed of multiple substances. Ni₃S₂@Ni₂P/MoS₂ only requires a low overpotential (η₁₀) of 175 mV at a current density of 10 mA cm^-2 in 1.0 M KOH solution and the stable duration exceeds 40 h. In addition, this heterogeneous structure is assembled into an electrolytic cell for overall water splitting, which exhibits a low cell voltage of 1.61 volts and retains the robust stability over 30 h at 10 mA cm^-2. The Ni₃S₂@Ni₂P/MoS₂ heterostructure prepared in this research provides a strategy for exploring other heterostructured electrocatalysts with different components.

Construction of a C@MoS2@C sandwiched heterostructure for accelerating the pH-universal hydrogen evolution reaction

Herein a facile and versatile hydrothermal method has been developed to construct a polypyrrole-derived carbon nanotube (PCN), MoS2 nanosheets and a carbon shell integrated sandwich-like heterostructure (PCN@MoS2@C). This heterostructure shows excellent performance in the hydrogen evolution reaction (HER) over a wide pH range. The results indicate that the porous carbon shell coated heterostructure provides MoS2 nanosheets with sufficient conductivity, increased number of active sites, and strong structural stability, and thus boosts its HER performance.