Crystal facet optimization in cadmium sulfide/reduced graphene oxide-based photosynthetic biohybrid systems for enhanced light-driven biohydrogen production

The development of photosynthetic biohybrid systems (PBSs) integrating inorganic light absorbers with non-photosynthetic bacteria innovate wastewater valorization via organics bioconversion, yet interfacial electron transfer bottlenecks limit efficiency. To address this, we regulated crystal facet exposure ratios in cadmium sulfide/reduced graphene oxide (CdS/RGO) through hydrothermal synthesis time control, observing facet-dependent activity trends. The optimized biohybrid achieved a maximum hydrogen yield of 2195.3 μmol (233.6 µmol·g −1 ·h −1 over 8 h), representing a 295 % enhancement over unmodified PBSs. Density functional theory (DFT) calculations revealed that increased exposure of high-activity (1   0   3) and (1   1   2) facets correlated with reduced work function values, promoting electron emission. Synergistically combined with RGO’s electron-shuttling function, this facilitated charge transfer to bacterial outer membrane proteins. These results demonstrate facet engineering as a tunable strategy for enhancing electron donation capacity in PBSs, offering design principles for biohybrid systems.