Tingxue Fang,Jiawei Wang,Zongxuan Bai,Yuhao Wang,Nan Wang,Dong Xiang,Kedi Cai
It remains critical and challenging to synthesize non-noble metal catalysts with excellent hydrogen evolution reaction (HER) activity in a wide pH range. High-temperature pyrolysis is one of the main methods for catalyst synthesis but can be time-consuming and leads to agglomeration easily. In view of this, molybdenum carbide and molybdenum nitride composite (MoC@MoN) was prepared via CO2 laser irradiation technology. The catalytic activity of the as-prepared catalysts can be effectively regulated by controlling the usage of Na2MoO4·2H2O and the applied CO2 laser power. In acidic and alkaline media, the as-prepared MoC@MoN requires an overpotential of only 63 mV and 34 mV, respectively, at a current density of 10 mA cm–2 and exhibits considerable electrochemical and structural durability, making it a suitable candidate for hydrogen production in a wide pH range. Theoretical calculations reveal the surface adsorption and desorption properties of reactive hydrogen and confirm the energetically favorable hydrogen spillover on the heterostructured MoC@MoN interface. The construction of the heterostructured interface enhances the activation of H2O* and further decreases the energy barrier of H2O* dissociation, thereby promoting the Volmer step and the H* supply for HER on the MoC@MoN interface. The integration of efficient H* adsorption on MoN and easy desorption on MoC effectively accelerates the Tafel step and hydrogen spillover, resulting in excellent HER performance of MoC@MoN. The strategy presented in this paper may offer a unique and viable approach for designing and synthesizing high-performance, low-cost HER catalysts, applied in a wide pH range.
Developing highly active and stable electrocatalysts for practical proton exchange membrane water electrolyzers (PEMWEs) operating at industry-relevant current densities remains a significant challenge. In particular, the hydrogen evolution reaction (HER) at ampere-level current densities leads to the rapid consumption of interfacial protons, resulting in sluggish kinetics. Herein, a strategy is proposed to reduce the proton transfer energy barriers and improve the HER kinetics at high current densities by anchoring tri-lacunary Keggin-type polyoxometalates (POMs) on Pt. The lacunary POMs clusters function as proton pumps, increasing the connectivity of hydrogen bond networks and enabling proton transfer via a proton-coupled electron transfer mechanism. In addition, an unconventional Tafel step mediated by short-pathway hydrogen spillover from POMs clusters to Pt active sites is also created. As a result, an ultra-high mass activity of 782.94 A·mg Pt −1 and remarkable durability over 6000 h at a current density of 2000 mA·cm −2 can be simultaneously achieved in a practical PEMWE with an ultralow Pt loading mass of 4.2 µg Pt ·cm −2 . The strategy provides new opportunities in developing next-generation low-Pt electrocatalysts for PEMWE applications.
危险品化学品经营许可证（带存储）