Fabricating High-Quality Cu2O Photocathode by Magnetron Sputtering: Insight into Defect States and Charge Carrier Collection in Cu2O

Earth-abundant Cu2O comprises one of the best-performing photocathodes for solar-driven water splitting that provides a sustainable solution for the energy crisis. However, typical Cu2O photocathodes based on widespread electrochemical deposition (ED-Cu2O) hit a bottleneck in pursuing higher efficiency due to ED-Cu2O's inadequate electrical properties and excessive detrimental defects, demonstrating the need to explore alternative methods to fabricate a high-quality Cu2O film for further development of Cu2O photoelectric conversion. Here, commercial magnetron sputtering (MS) is exploited to manufacture a Cu2O photocathode (MS-Cu2O) with an appreciable electrical property and diminished point defects. Comprehensive optoelectronic properties characterization and energy band simulations unveil that the synchronous enhancement in electronic properties and charge carrier lifetime of MS-Cu2O benefiting from its suppressed defects relative to ED-Cu2O synergistically boosts its carrier collection efficiency and PEC performance. This work demonstrates the potential of MS in fabricating an energetic Cu2O photocathode to push the advancement of Cu2O photoelectrochemical catalysis.