Semi-artificial photosynthesis bridges the fields of materials science and chemical biology for the sustainable synthesis of solar fuels . It benefits from the evolution and bioengineering of enzymes, enabling complex chemical conversions with high selectivity and efficiency . Materials chemistry provides an avenue to rationally wire these enzymes to semiconducting light-harvesters, adopting a modular approach where individual components can be optimised separately for photoelectrochemical (PEC) applications . However, a challenge in the assembly of biohybrid PEC systems remains the frequent need for kinetically-fast buffers (to offset pH gradients) and diffusional mediators (to transfer charge from light absorber to biocatalyst) that prevent sustainable and stable semi-artificial photosynthesis. These components are not only expensive , but are also often noninnocent as they can be easily oxidised at low overpotentials by the photoanode , which precludes the coupling of fuel production with stoichiometric O2 evolution. Moreover, existing enzymatic biohybrid PEC devices are based on photoactive materials such as silicon , perovskite and Cuchalcogenide , often limited by either insufficient photovoltages for constructing bias-free devices, moisture degradation, material toxicity or high costs.