Structural control of heterostructured Co3N-Co nano-corals for boosting electrocatalytic hydrogen evolution based on insulator-confined plasma engineering

A facile phase reconfiguration has been considered as an essential issue in achieving heterostructures for boosting the electrocatalytic H2 production. Compared to chemical approaches, plasma-based technique serves as a favorable strategy to achieve hetero-structured nano-frameworks, but its modulation on nano-structured precursor inevitably leads to multi-step fabrication process and it is difficult to precisely control the partial surface modulation through plasma technique due to complicated interaction environment. To achieve heterostructures with optimized hydrogen evolution reaction (HER) behavior, we design a novel auxiliary insulator-confined plasma system to directly achieve Co3N-Co heterostructure (hCNC) with favorable activity by controlling surface heating process during plasma nitridation. The resultant hCNC nano-framework delivers excellent catalytic performance, evidenced by its overpotential of 97 and 229 mV at current density of 10 and 100 mA cm−2 for HER in alkaline condition, in stark comparison with that of normal plasma fabricated Co3N. Operando plasma diagnostics along with numerical simulation further confirm the effect of surface heating on typical plasma parameters as well as the Co3N-Co nano-structure, indicating the key factor responsible for the high-performance hetero-structured electrocatalyst.