Near-infrared-driven photoelectrocatalytic oxidation of urea on La-Ni-based perovskites

The solar-driven photoelectrocatalytic oxidation of urea is an efficient and costly way to produce hydrogen and purify wastewater synergistically. However, it is still a big challenge facing to the semiconductor-catalyst photoanode with high utilization of sunlight. Herein, we report a series of La-Ni-based Ruddlesden-Popper phases perovskite materials (Lan+1NinO3n+1, n = 1, 2 and 3) for photoelectrocatalytic oxidations of urea. Such La-Ni -based perovskite materials act simultaneously as a light-harvesting semiconductor and as the electrocatalyst for urea oxidation and all of Lan+1NinO3n+1 catalysts display a strong near-infrared (NIR) light absorption (>= 800 nm). The La4Ni3O10 catalyst exhibits the best activity towards urea oxidation reaction (UOR) with an applied potential of 1.54 V vs. RHE at 1 mA cm-2, compared to that of 1.64 V and 1.56 V vs. RHE for La2NiO4 and La3Ni2O7, respectively, and 44.7 mu mol cm-2h-1 of N2 generation rate under NIR light irradiation at the potential of 1.62 V vs. RHE, which is 2.5 times and 1.8 times of that for La2NiO4 and La3Ni2O7, respectively. The unique structure of La4Ni3O10 accelerates the separation and transport of electrons and holes, which is beneficial for the diffusion and adsorption of urea molecules in photoanode.