The rational design and strategy of obtaining stable bifunctional electrocatalysts with unique functionalities are prerequisite to achieving robust catalytic activity. In this study, a composition-controlled partial sulfurization/phosphorization strategy to synthesize a doughnut-like 3D heterostructured electrocatalyst for overall water splitting is proposed, wherein core–shell 2D CoS1−xPx nanosheets decorated with N-doped carbon are self-assembled to form a hierarchical 3D architecture. The composition and phase structure in core–shell CoS1−xPx can be readily modified by controlling the liquid phase sulfurization and subsequent phosphorization, thereby modifying the electronic structure and activating the intrinsic active sites. The resulting CoS1−xPx benefits from the unique structural features including high accessible active surface area, adequate amount of reactive sites, intimate interfacial coupling between the components, interconnected electron highway, and accelerated charge/mass transfer ability. Consequently, the optimized CoS0.46P0.54 electrocatalyst achieves a catalytic current density of 10 mA cm−2 at overpotentials as low as 101 and 302 mV for hydrogen evolution reaction and oxygen evolution reaction, respectively, with outstanding long-term operational stability in alkaline solution. The CoS0.46P0.54 couple enables an alkaline water electrolysis with a current density of 10 mA cm−2 at a low cell voltage of 1.62 V, comparable to that of the RuO2||Pt/C couple (1.6 V).
Bibliographical noteFunding Information:
This work was supported by a National Research Foundation (NRF) of Korea grant (No. 2012R1A3A2026417) and the Creative Materials Discovery Program (NRF-2018M3D1A1058793) funded by the Ministry of Science and ICT.
All Science Journal Classification (ASJC) codes
- Materials Science(all)