Dual co-catalysts decorated Zn-WO3 nanorod arrays with highly efficient photoelectrocatalytic performance

WO3 has been recognized as a promising photoanode for the conversion of solar energy to hydrogen energy through photoelectrochemical water splitting. Herein, Zn-WO3 nanorod arrays were synthesized by a two-step solvothermal method and then decorated with FeOOH and CoOOH dual co-catalysts layer through electrodeposition. Characterizations confirm the presence of abundant surface oxygen vacancies in Zn-WO3, leading to the increase of carriers with high mobility and thus improving the separation (from 63.7% to 92.0%) and injection (from 61.9% to 95.3%) efficiency of carriers. Meanwhile, the dual co-catalysts layer accelerates the transfer of the hole at the interface and inhibits the photocorrosion. Consequently, the optimal 9-Zn-WO3-Fe/Co exhibits the photocurrent of 3.63 mA/cm2 at 1.23 V vs. RHE, which is 90.7% of the theoretical value of WO3 (ca. 4.0 mA/cm2). This work constructs a highly efficient and stable WO3 photoanode by an integration strategy of transition metal doping and dual co-catalysts modification.