Molybdenum-tungsten Oxide Nanowires Rich in Oxygen Vacancies as An Advanced Electrocatalyst for Hydrogen Evolution

Molybdenum tungsten hydrogen oxide doped with phosphorus for enhanced oxygen/hydrogen evolution reactions

The development of efficient electrocatalysts for hydrogen and oxygen evolution reactions (HER and OER) is pivotal for advancing cleaner and sustainable fuel production technologies. The conventional electrocatalysts have limited stability and higher overpotentials, and there is demand to explore advanced materials and synthesis methods. In this context, a novel bifunctional electrocatalyst has been devised through the phosphidation of tungsten molybdenum oxide (P-Mo0.69W0.31H0.98O3) at relatively low temperatures. This innovative approach aims to enhance the efficiency of HER and OER while minimizing the overpotential values and maintaining higher stability. Specifically, the individual performance of Mo0.69W0.31H0.98O3 has been significantly boosted by doping it with phosphorus at a low temperature of 300 °C. This doping process results in a unique morphology for the catalyst, leading to a notable improvement in OER/HER performances. P-Mo0.69W0.31H0.98O3 exhibits a potential of 320 mV at 10 mA cm-2 in a KOH electrolyte, demonstrating both high activity and long-term stability. Additionally, P-Mo0.69W0.31H0.98O3 exhibits commendable HER performance, requiring only 380 mV at 100 mA cm-2. This combination of efficient OER and HER performance positions P-Mo0.69W0.31H0.98O3 as representing a significant advancement in the field of electrocatalysis, additionally addressing the fundamental gap by providing stable and hybrid catalyst for various electrochemical devices. Given its cost-effectiveness and exceptional activity, P-Mo0.69W0.31H0.98O3 holds significant potential for advancing the field of electrocatalysis and contributing to the development of cleaner and sustainable fuel production methods.

Optimization Methods of Tungsten Oxide-Based Nanostructures as Electrocatalysts for Water Splitting

Electrocatalytic water splitting, as a sustainable, pollution-free and convenient method of hydrogen production, has attracted the attention of researchers. However, due to the high reaction barrier and slow four-electron transfer process, it is necessary to develop and design efficient electrocatalysts to promote electron transfer and improve reaction kinetics. Tungsten oxide-based nanomaterials have received extensive attention due to their great potential in energy-related and environmental catalysis. To maximize the catalytic efficiency of catalysts in practical applications, it is essential to further understand the structure-property relationship of tungsten oxide-based nanomaterials by controlling the surface/interface structure. In this review, recent methods to enhance the catalytic activities of tungsten oxide-based nanomaterials are reviewed, which are classified into four strategies: morphology regulation, phase control, defect engineering, and heterostructure construction. The structure-property relationship of tungsten oxide-based nanomaterials affected by various strategies is discussed with examples. Finally, the development prospects and challenges in tungsten oxide-based nanomaterials are discussed in the conclusion. We believe that this review provides guidance for researchers to develop more promising electrocatalysts for water splitting.

Molybdenum oxide-iron, cobalt, copper alloy hybrid as efficient bifunctional catalyst for alkali water electrolysis

Efficient and durable non-precious catalyst for both hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) is pivotal for practical water electrolysis toward clean hydrogen fuel. Herein, a molybdenum oxide-FeCoCu alloy hybrid (MoO_x-FeCoCu) catalyst was designed by polyoxometallate (POM) molecular cluster mediated solvothermal alcoholysis and ammonolysis of metal salts followed by pyrolytic reduction treatment. The HER efficiency is substantially enhanced by the ternary alloy component, which is more close to the benchmark Pt/C catalyst, and the HER catalytic stability is also superior to Pt/C catalyst. Moreover, the MoO_x-FeCoCu demonstrates high catalytic efficiency and rather good durability for OER. Benefitted by the bifunctional catalytic behaviors for HER and OER, the symmetric water electrolyzer based on the MoO_x-FeCoCu electrode requires a low driving voltage of 1.69 V to deliver a response current density of 10 mA cm^-2, which is comparable to that based on the benchmark Pt/C HER cathode and RuO₂ OER anode. The current work offers a feasible way to design efficient bifunctional catalyst for water electrolysis via POM mediated co-assembly and calcination treatment.

Amorphous materials for elementary-gas-involved electrocatalysis: an overview

Given the critical demands on energy conversion, storage, and transportation, tremendous interest has been devoted to the field of material development related to energy harvesting, recently. As the only route towards energy utilization, the carriers with the characteristics of low carbon are regarded as the future choice, e.g., hydrogen and ammonia. To this end, electrocatalysis provides a green way to access these substances. However, the unfulfilled conversion efficiency is the bottleneck for practical application. In this review, the promising characteristics of amorphous materials and the amorphous-induced electrocatalytic enhancement (AIEE) were emphasized. In the beginning, the characteristics of amorphous materials are briefly summarized. The basic mechanism of heterogeneous electrocatalytic reactions is illustrated, including the hydrogen/oxygen evolution and oxygen/nitrogen reduction. In the third part, the electrocatalytic performance of amorphous materials is discussed in detail, and the mechanism of AIEE is highlighted. In the last section of this review, the challenges and outlook for the development of amorphous enhanced electrocatalysis are presented.