“…Particularly, cobalt-based OER electrocatalysts such as cobalt sulfides, [17][18][19] cobalt oxides/hydroxides [12,[20][21][22][23][24][25][26][27] and single cobalt sites [3,13,[27][28][29][30] have attracted considerable attention. Various design strategies concerning vacancy/defect tailoring, [13,18,28,[30][31][32][33] doping [8,13,14,17,30,31,[34][35][36] and heterojunction engineering, [4,18,21,23,[37][38][39][40] as well as strain tuning engineering [16,32] have been exploited.…”