Ternary non-noble metal zinc-nickel-cobalt carbonate hydroxide cocatalysts toward highly efficient photoelectrochemical water splitting

TiO2 photoanodes have aroused intensive research interest in photoelectrochemical (PEC) water splitting. However, they still suffer from poor electron-hole separation and sluggish oxygen evolution dynamics, leading to the low photoconversion efficiency and limiting commercial application. Here, we designed and fabricated novel ternary non-noble metal carbonate hydroxide (ZNC-CH) nanosheet cocatalysts and integrated them with TiO2 nanorod arrays as highly efficient photoanodes of PEC cells. Compared with the pristine TiO2, the photocurrent of photoanode with the optimal amount of ZNC-CH represents 3.2 times enhancement, and the onset potential is shifted toward the negative potential direction of 62 mV. The remarkable enhancement is attributed to the suppressed carrier recombination and enhanced charge transfer efficiency at the interface of TiO2, ZNC-CH and electrolyte, which is closely related to the zinc elements modulated intrinsic activity of catalysts. Our results demonstrate that the introduction of multimetallic ZNC-CH cocatalysts onto photoanodes is a promising strategy to improve the PEC efficiency.