Journal
ACS APPLIED ENERGY MATERIALS
Volume 3, Issue 6, Pages 5219-5228Publisher
AMER CHEMICAL SOC
DOI: 10.1021/acsaem.0c00045
Keywords
catalysis; electrochemistry; hydrogen evolution reaction; molybdenum oxide; metal/oxide interface
Funding
- National Natural Science Foundation of China [11227902, 21902103]
- Science and Technology Committee of Shanghai [14520722100]
- Certificate of China Postdoctoral Science Foundation [2015LH0031]
- Hundred Talents Program of the Chinese Academy of Science
- ME2 project under National Natural Science Foundation of China [11227902]
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By tuning interfacial structures, we have achieved an extremely small Tafel slope of 34.4 mV dec(-1) for the hydrogen evolution reaction (HER) over a molybdenum oxide catalyst in an acidic electrolyte. Such a small Tafel slope indicates the presence of active sites following the Volmer-Tafel mechanism, which is almost exclusively observed on platinum group metals. We attribute this excellent kinetic property to the enhancement effect from the metal/metal oxide Mo/MoOx) interface in the catalysts. This Mo/MoOx interface was obtained by tuning the hydrogen annealing method. Density functional theory calculations suggest that the hydrogen spillover from the Mo surface to the MoOx surface through an optimized interface will increase the hydrogen coverage on the MoOx surface. Thus, the hydrogen adsorption energy on MoOx can be reduced, making the recombination of the surface hydrogen feasible. Hydrogen temperature-programmed reduction provides clear evidence of hydrogen spillover from Mo to MoO2 at the Mo/MoO2 interfaces. Hence, the above Mo/MoOx interface will also lead to a high HER activity, as demonstrated by the high turnover frequency per active site (at 100, 150, and 200 mV vs the reversible hydrogen electrode, the values are approximately 0.004, 0.249, and 1.398 H-2 respectively). Our study demonstrates a new route to design low-cost-efficient HER catalysts of nonprecious metals by tuning transition metal/oxide interfaces.
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