Band Structure Engineering toward Low-Onset-Potential Photoelectrochemical Hydrogen Production

Photoelectrochemical (PEC) hydrogen production can directly and effectively convert solar energy to clean and sustainable hydrogen energy. However, taking the photoanode as an example, the onset potential ( V onset ) of the photoanodic current is too positive, which is not conducive to the improvement of energy conversion efficiency and thus hinders the practical application of PEC hydrogen production. Here, we demonstrate a new quaternary alloy nanowire photoanode with low V onset and high solar conversion efficiency constructed by a narrow-bandgap semiconductor CdSeTe and a wide-bandgap semiconductor CdS, a strategy that enables the energy band modulation by adjusting the molar ratio of the two semiconductors. Through the modulation of the band structure, the negative shift in the V onset of the PEC hydrogen production can be realized, so that high photocurrent is achieved under a lower bias voltage. As a result, we cathodically shifted the V onset by 0.7 V RHE on the alloyed cadmium-based chalcogenide photoanode under 1-sun light. This strategy of using energy band modulation to achieve a lower V onset and high energy conversion efficiency will provide more possibilities for the industrial application of PEC hydrogen production.