Simultaneous Heteroatom Doping and Microstructure Construction by Solid Thermal Melting Method for Enhancing Photoelectrochemical Property of g-C3N4 Electrodes

Abstract A phosphorus (P) doped g-C3N4 needle (PCNN) electrode with great photoelectrochemical (PEC) property is fabricated by a facile solid thermal melting approach. The proposed thermal melting method owns the advantages of low-cost, simple and easy operation, as only the solid mixing of melamine (C and N precursor) and triphenylphosphine oxide (P precursor) is needed in electrode preparation procedure. This method is further conducive to the formation of uniform film with doped heteroatom and unique microstructure on fluorine-doped tin oxide- coated glass (FTO). The PCNN photoelectrode holds a tip structure, which highly inhibits the recombination of photo-generated electron and hole. Particularly, the doped P in PCNN can further accelerate the photo-generated carrier separation and enhance the optical absorption property. As a result, the PCNN photoelectrode displays a five-fold enhancement of photocurrent density over pristine g-C3N4, reaching up to 127.4 µA cm-2 at 1.23 V versus reversible hydrogen electrode (RHE), as well as good optical, chemical and physical stability. The PCNN photoelectrode further exhibits great property in PEC removal of pollutant in water. This study provides an effective fabrication method and opens new avenues for the significant improvement of g-C3N4 based electrode in their various energy conversion and environmental application.