Highly active and stable CuAlOx/WO3 photoanode for simultaneous pollutant degradation, hydrogen and electricity generation

An unassisted solar water-energy nexus system (SWENS) based on an ultra-thin CuAlOx overlayer coated WO3 nanoplate array (CuAlOx/WO3) photoanode, a rear silicon solar cell and a Pt-black/Pt cathode was proposed to efficiently degrade refractory organic pollutants and simultaneously produce hydrogen and electricity. The formed p-n junction between p-type CuAlOx and n-type WO3 effectively facilitated the charge separation in the CuAlOx/WO3 photoanode. Moreover, the CuAlOx overlayer enhanced the capture of photogenerated holes and isolated WO3 from the solution, thereby improving the charge transfer and inhibiting the photocorrosion of WO3. Therefore, the optimized CuAlOx/WO3 photoanode showed a significantly enhanced and stable photocurrent density of-2.82 mA cm-2 at 1.0 V vs. Ag/AgCl, which was-4 times higher than that of the pristine WO3. Based on this outstanding photoelectrocatalytic performance, the assembled SWENS showed a degradation efficiency of nearly 100% for tetracycline, a hydrogen generation rate of-26.8 mu mol center dot h-1 center dot cm- 2 and a power density of-593 mu W cm-2 under simulated solar light illumination. Our SWENS also exhibited outstanding universality in degrading various refractory organic pollutants for green energy production.