Hydrogen produced from electrolysis of water driven by electricity is many researchers' desire. However, unstable electrocatalysts and low energy-conversion efficiency limit the development of this method.

Prof. MA Mingming's Group from University of Science & Technology of China of Chinese Academy of Sciences came up with a facile approach to synthesis cobalt-nanocrystal-assembled hollow nanoparticles (Co-HNP), which can serve as a highly active and stable electrocatalyst for hydrogen evolution reaction (HER) from neutral-pH water. This step is expected to promote the electrocatalytic hydrogen generation development.

Researchers synthesized the Co-HNP by “sacrificial template” method with the CoWO₄ NPs serving as the templates. In order to evaluate HER activity, the researchers also tested Blank CC, cobalt metal plate and commercial Pt/C catalyst (20wt% Pt on Vulcan XC-72). Results revealed that both blank CC and cobalt metal plate show negligible HER activity, Pt/C shows superior HER activity with near-zero overpotential and Co-HNP exhibits an excellent activity with a low onset of 23 mV and a small Tafel slope value of 38 mVdec^-1. Moreover, the Co-HNP/CC electrode can produce a high current density of 150 mA cm^-2 at a relatively low overpotential of 290 mV.

Researchers also examined the durability of Co-HNP as electrocatalysts. The Co-HNP/CC electrode retains its high activity after 20h hydrogen generation at a high current density of 150 mA cm^-2. This suggests the superior activity and stability of Co-HNP as electrocatalyst.

This research elucidated that stabilized non-noble metal nanocrystals assembled in hollow nanostructures are desirable for developing highly active and stable electrocatalysts. The work was chosen as the inside cover of Angew. Chem. Int. Ed.

This work was supported by the National Natural Science Foundation of China (21474094) and the Recruitment Program of Global Experts.

Figure: The work was selected as the inside cover. (Cedit: Angew. Chem. Int. Ed)