Ru nanoparticles have been demonstrated to be highly active electrocatalysts for the hydrogen evolution reaction (HER). At present, most of Ru nanoparticles-based HER electrocatalysts with high activity are supported by heteroatom-doped carbon substrates. Few metal oxides with large band gap (more than 5 eV) as the substrates of Ru nanoparticles are employed for the HER. By using large band gap metal oxides substrates, we can distinguish the contribution of Ru nanoparticles from the substrates. Here, a highly efficient Ru/HfO2 composite is developed by tuning numbers of Ru-O-Hf bonds and oxygen vacancies, resulting in a 20-fold enhancement in mass activity over commercial Pt/C in an alkaline medium. Density functional theory (DFT) calculations reveal that strong metal-support interaction via Ru-O-Hf bonds and the oxygen vacancies in the supported Ru samples synergistically lower the energy barrier for water dissociation to improve catalytic activities.
Ammonia is an important chemical raw material, widely used in industry and agriculture, as well as an important energy storage intermediate and carbon‐free energy carrier. But, its production is limited to the traditional Haber‐Bosch process. Recently, electrochemical reduction of N2 has been attracting more and more attention, owing to the lower energy consumption and because it is environmentally friendly. However, there are a lot of problems that remain to be solved, and the main challenges are the low selectivity and catalytic activity when using this process. In this Review, we first summarize the recent development of electrocatalysts for electrochemical N2 reduction and elaborate on the reaction mechanisms of the nitrogen reduction reaction (NRR). In addition, the effects of different types of electrolyte on the NRR activity and electrolyte choice are discussed. Finally, the perspectives of electrochemical nitrogen reduction for conversion to ammonia are discussed.
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