Enhancing the Lifetime of Photoinduced Charge Carriers in CuFeO2 Nanoplates by Hydrothermal Doping of Mg for Photoelectrochemical Water Reduction

Highly active and stable photocathodes are desirable for efficient photoelectrochemical water reduction. However, most photocathode materials suffer from the short lifetime of photoinduced charge carriers resulting in low energy conversion efficiency. Herein, the authors present a novel strategy to enhance the lifetime of photoinduced charge carriers for hexagonal CuFeO2 platelets based photocathode. The enhancement is realized by simply hydrothermal doping of Mg into CuFeO2. Quantitative phase composition analysis and characterizations are carried out for the Mg doped CuFeO2 materials with varied doping contents. This doping route not only induces to more acceptor-type states to increase the p-type carrier concentration, but also improves conductivity of CuFeO2 and facilitates easier carriers transport, which are the key factors for the lifetime enhancement. After systematical tuning of the doping amount, the authors find that when the Mg content reaches 0.1%, the CuFeO2 presents the longest lifetime for the photoinduced charge carriers (0.8485s) referring to an enhancement of 94% in the lifetime compared with pure CuFeO2.