Plasma-induced N doping and carbon vacancies in a self-supporting 3C-SiC photoanode for efficient photoelectrochemical water oxidation

Due to its suitable bandgap and excellent stability, 3C-SiC is being investigated as one of the promising candidates for photoelectrochemical (PEC) water oxidation. However, the limited surface activity and short carrier lifetime prevent 3C-SiC photoanodes from facilitating efficient PEC water splitting. To tackle these problems, this work proposes a plasma technique to control the crystal structure and optical characteristics of 3C-SiC. Nitrogen plasma induces carbon vacancies (V_c) and Si-N bonds, further leading to a narrower bandgap of 3C-SiC. The combination of V_c and N doping enhanced the light trapping capability of the electrode, thereby improving the efficiency of electron-hole pair separation and charge transfer, resulting in an accelerated water oxidation reaction, i.e., photocurrent density (2.50 mA cm⁻² at 1.23 V_RHE) increased by 7.6 times compared to that of pristine SiC. This work offers an effective strategy for regulating the electronic structure of SiC-based photoanodes by plasma treatment, which may be extended to other photoelectrodes for PEC application.