Laser Subtracting Multinary Metal Oxides Activates Photoassisted Discharge in Li-O₂ Battery

Utilizing photo-generated carriers to boost charge–discharge process is of significance in photo-assisted lithium-oxygen batteries (PLOBs), while this poses a great challenge for low-cost multinary metal oxides (MMOs) photoelectrodes on the unfavorable conduction band that is generally lower than the reduction potential of Li₂O₂ to Li. The present work demonstrates a universal strategy of laser subtracting bulk MMOs, yielding gram-scale MMOs nanocrystals with a favorable band position that allows for photo-generated electrons to participate in photo-assisted reduction of oxygen. The extreme conditions manufacturing endows the MMO nanocrystals with unique surface states with abundant Lewis acid-base sites, which is experimentally verified to be favorable for acceleration of electrochemical reaction kinetics in PLOBs. Exemplified by photoelectrodes comprising laser-subtracted BiVO₄ (BVO) NCs with elevated conduction band and tailored surface states, which achieve a high discharge potential of 3.25 V and low charge potential of 2.98 V (0.1 mA cm⁻²) with a round-trip efficiency of 109%, and excellent cycling stability over 255 cycles with only 0.027% capacity decay per cycle, surpassing previously reported metal oxide-based cathodes in PLOBs. Such a laser-subtracting strategy was further found to be general in yielding many other MMOs NCs with activated photo-assisted discharge behaviors, thus paving an efficient way to discover potential bifunctional photoelectrodes for PLOBs based on laser-matter interactions.