Plasma Engineering of Oxygen-Vacancy-Rich BiOCl Nanosheets for Efficient Photocatalytic Cofactor Regeneration

Abstract Efficient regeneration of the coenzyme NADH is a key challenge for sustainable biomanufacturing. Conventional regeneration strategies often depend on stoichiometric chemical reductants or complex multi‑enzyme systems, which introduce economic and environmental constraints. This study presents a green and efficient photocatalytic method for NADH regeneration using BiOCl nanosheets with tailored oxygen vacancy (VO) concentrations, fabricated via mild plasma engineering. This approach operates under ambient conditions, eliminating the need for high temperature, high pressure, or hazardous reductants, such as hydrogen or sodium borohydride, thereby reducing safety risks and environmental impact. The introduced oxygen vacancies serve as effective electron traps, significantly suppressing charge recombination, enhancing photogenerated charge separation, and extending the light-harvesting range, which collectively improve solar energy utilization. At an optimized VO concentration, the modified BiOCl nanosheets achieve a NADH regeneration yield of 94.1%, representing a 2-fold increase over pristine BiOCl. Notably, the system exhibits an apparent quantum efficiency of 2.04% at 380 nm, which is 3.7 times higher than that of unmodified BiOCl. To the best of our knowledge, this performance is at the forefront of the current field of photocatalytic coenzyme regeneration. This work provides a green and controllable pathway for defect engineering in photocatalysts and establishes a systematic platform for plasma‑assisted catalyst design toward sustainable biophotonic energy conversion.