Strain induced rich planar defects in heterogeneous WS/WO enable efficient nitrogen fixation at low overpotential

• Published in: Journal of materials chemistry. A, Materials for energy and sustainability Materials for energy and sustainability, 2020-07, Vol.8 (26), p.12996-133
• Main Authors: Ling, Ying, Kazim, Farhad M. D, Ma, Shuangxiu, Zhang, Quan, Qu, Konggang, Wang, Yangang, Xiao, Shenglin, Cai, Weiwei, Yang, Zehui
• Format: Article
• Language: English
• ISSN: 2050-7488; 2050-7496
• DOI: 10.1039/c9ta13812a

Suppression of the competitive hydrogen evolution reaction (HER) and creation of new active sites have been considered to be the most effective methodology to design efficient electrocatalysts for the nitrogen reduction reaction (NRR). Here, we report a heterogeneous WS 2 /WO 2 electrocatalyst with abundant planar defects at the heterointerface ascribed to the strain effect induced by the mismatched lattice spacing between WS 2 and WO 2 , which enables efficient electrocatalysis toward the NRR with a faradaic efficiency of 13.5% and an NH 3 yield rate of 8.53 μg NH 3 h −1 mg cat. −1 at −0.1 V vs. RHE in acidic medium compared to bare WS 2 with a faradaic efficiency of 7.87% and an NH 3 yield rate of 6.99 μg NH 3 h −1 mg cat. −1 . The superior NRR electrocatalytic activity of heterostructured WS 2 /WO 2 is attributed to the introduction of WO 2 effectively impeding the HER catalysis because of the blocking of edge defects in WS 2 and simultaneously creating planar defects at the WS 2 /WO 2 heterointerface as active sites for stable NRR catalysis. The extraordinary NRR electrocatalytic activity of WS 2 /WO 2 is further confirmed by NMR measurements and density functional theory (DFT) calculations demanding comparably lower uphill free energy for the rate-determining step of NRR catalysis, i.e. formation of NNH species. This work offers useful information for constructing efficient NRR electrocatalysts. Incorporation of WO 2 to WS 2 nanosheets can efficiently suppress the competitive hydrogen evolution reaction (HER) due to the reduction of edge defects and create new planar defects at heterointerfaces for nitrogen reduction reaction (NRR).