BiVO 4 /Bi:NiO/Co–Ci photoanode and BiVO 4 –Cu 3 BiS 3 tandem cell for unbiased solar hydrogen evolution and simultaneous urea oxidation

Integration with a Cu 3 BiS 3 photocathode enables a BiVO 4 –Cu 3 BiS 3 tandem cell for unbiased, solar-driven, coupled urea oxidation and hydrogen evolution, delivering a photocurrent density of 2.0 mA cm −2 and stable operation exceeding 20 hours.