Wittichenite semiconductor of Cu3BiS3 films for efficient hydrogen evolution from solar driven photoelectrochemical water splitting

A highly efficient, low-cost and environmentally friendly photocathode with long-term stability is the goal of practical solar hydrogen evolution applications. Here, we found that the Cu 3 BiS 3 film-based photocathode meets the abovementioned requirements. The Cu 3 BiS 3 -based photocathode presents a remarkable onset potential over 0.9 V RHE with excellent photoelectrochemical current densities (~7 mA/cm 2 under 0 V RHE ) and appreciable 10-hour long-term stability in neutral water solutions. This high onset potential of the Cu 3 BiS 3 -based photocathode directly results in a good unbiased operating photocurrent of ~1.6 mA/cm 2 assisted by the BiVO 4 photoanode. A tandem device of Cu 3 BiS 3 -BiVO 4 with an unbiased solar-to-hydrogen conversion efficiency of 2.04% is presented. This tandem device also presents high stability over 20 hours. Ultimately, a 5 × 5 cm 2 large Cu 3 BiS 3 -BiVO 4 tandem device module is fabricated for standalone overall solar water splitting with a long-term stability of 60 hours.