Surface passivation of natural photosystem-based photoelectrode for efficient and sustainable bio-photovoltaic applications

Abstract

Natural photosystems exhibit a high light-harvesting efficiency, which arises from the sophisticated self-assembly of pigments, making them promising for bio-photovoltaic devices. However, their integration into such devices is very challenging due to the photosystem's intrinsic instability, which hinders their durable immobilization to electrodes and efficient charge transfer at interfaces. Here we report a new approach to overcome these problems by employing the atomic layer deposition of amorphous TiO2 for the robust immobilization and stabilization of photosystem I (PSI) on a mesoporous TiO2 (mp-TiO2) photoanode. This approach not only stabilizes the PSI against the harsh conditions of photoelectrochemical operations but also enhances electron transfer by passivating the PSI and mp-TiO2 interfaces. The protective effect increases with increasing the amorphous TiO2 thickness up to 20 nm, beyond which a reduction in photocurrent is observed due to limited electron mobility through the amorphous oxide layer. Our findings demonstrate that such atomic layer deposition of a thin oxide layer holds great potential for improving the efficiency and stability of photosystem-based bio-photovoltaic devices. © 2025 The Korean Society of Industrial and Engineering Chemistry