Regulating the type of cobalt porphyrins for synergistic promotion of photoelectrochemical water splitting of BiVO4

Abstract Three novel semiconductor composite photoanodes (BiVO4/GO/CoTPP(OH)n, n = 1, 4 and 8) are designed and prepared by decorating BiVO4 with graphene oxide (GO) and cobalt porphyrins bearing different number of hydroxyl groups. The introduction of GO and CoTPP(OH)n onto the BiVO4 surface has been confirmed by transmission electron microscopy, scanning electron microscopy, X-ray photoelectron spectroscopy, X-ray diffraction, Fourier transform infrared and Raman spectroscopic techniques, endowing BiVO4 with improved charge transfer and broadened light absorption ability. Their viability as photoelectrochemical system is investigated under AM 1.5 G light irradiation, the photoelectrochemical water splitting performance being found to be dependent on the type of cobalt porphyrins. The BiVO4/GO/CoTPP(OH)4 is found to exhibit the largest photocurrent density of 5.27 mA/cm−2 at 1.23 V vs. RHE due to a combination of mechanisms.