Integration of Amorphous/Crystalline CoS/Co3B2 Heterostructure with Coupled Electronic Engineering Toward Efficient and Stable Oxygen Evolution Reaction

Synergistically integrating amorphous electrocatalysts with crystalline phases not only endows the system with highly exposed active sites but also exhibits superior electron transport to the active sites, which can effectively improve the catalytic activity toward oxygen evolution reactions (OER). Here, we report that amorphous CoS nanosheets were vertically grown on crystalline Co 3 B 2 thin films (Co 3 B 2 -TF) to form a CoS/Co 3 B 2 heterostructure for alkaline OER. It exhibits a low overpotential of 296   mV at 10   mA   cm -2 and a satisfactory stability over 24   hours at high current density 100   mA   cm -2 , surpassing the commercial RuO 2 catalyst. The DFT calculations indicate that the unique amorphous/crystalline heterophase coupling in CoS/Co 3 B 2 results in electron transfer between the CoS and Co 3 B 2 , exposing more active sites and facilitating interfacial electron transfer, altering d -band center value, thereby improving the intrinsic OER activity. This work provides a new strategy for designing and development of heterostructured transition-metal borides as highly active, durable, and low-cost catalysts for OER.