P-Type Cu-Doped Zn0.3Cd0.7S/Graphene Photocathode for Efficient Water Splitting in a Photoelectrochemical Tandem Cell

By doping Cu(I) ions in Zn 0.3 Cd 0.7 S, a novel p-type Cu doped Zn 0.3 Cd 0.7 S modified graphene (Zn 0.3 Cd 0.7 S (Cu)/GR) film photocathode was prepared. The as-prepared p-type Zn 0.3 Cd 0.7 S (Cu)/GR photocathode and an n-type WO 3 /graphene (WO 3 /GR) photoanode were used to assemble a photoelectrochemical tandem cell. Through examination of the optoelectronic and photoelectrochemical properties of Zn 0.3 Cd 0.7 S (Cu)/GR and WO 3 /GR photoelectrode, we evaluate the feasibility of the tandem cell for overall water splitting under UV–vis light irradiation. The optimal Cu doping in Zn 0.3 Cd 0.7 S photocathode concentration was found to be 6%. The rates of hydrogen and oxygen evolved from this tandem cell with the optimal electrodes were 65.6 and 12.3 μmol g –1 h –1 (80.5 and 15.1 μmol cm –2 h –1 ), respectively. This study suggests a promising method for constructing an efficient photoelectrochemical tandem device for overall water splitting.