CoS 2 needle arrays induced a local pseudo-acidic environment for alkaline hydrogen evolution

• Published in: Nanoscale 2021-08, Vol.13 (32), p.13604-13609
• Main Authors: Chen, Guozhu, Li, HuangJingWei, Zhou, Yajiao, Cai, Chao, Liu, Kang, Hu, Junhua, Li, Hongmei, Fu, Junwei, Liu, Min
• Format: Article
• Language: English
• ISSN: 2040-3364; 2040-3372
• DOI: 10.1039/D1NR03221F

The alkaline electrocatalytic hydrogen evolution reaction (HER) is a potential way to realize industrial hydrogen production. However, the sluggish process of H 2 O dissociation, as well as the accumulation of OH − around the active sites, seriously limit the alkaline HER performance. In this work, we developed a unique CoS 2 needle array grown on a carbon cloth (NAs@C) electrode as an alkaline HER catalyst. Finite-element simulations revealed that CoS 2 needle arrays (NAs) induce stronger local electric field (LEF) than CoS 2 disordered needles (DNs). This LEF can greatly repel the local OH − around the active sites, and then promote the forward H 2 O dissociation process. The local pH changes of the electrode surface confirmed the lower OH − concentration and stronger local pseudo-acidic environment of NAs@C compared to those of DNs@C. As a result, the NAs@C catalyst exhibited a low HER overpotential of 121 mV at a current density of 10 mA cm −2 in 1 M KOH, with the Tafel slope of 59.87 mV dec −1 . This work provides a new insight into nanoneedle arrays for the alkaline HER by electric field-promoted H 2 O dissociation.