To demonstrate the effect of local chemical environment changes in confined electrodes, first a mesoporous indium-tin-oxide (mesoITO) film on fluorine-doped tin oxide-coated glass (synthesised 50 nm ITO particles, film thickness of 8.5 μm, Figures ) was chosen as the electrode. The mesoporous structure could be simulated as a randomly close packed structure and hence did not require too computationally expensive modelling. ITO was chosen as the electrode material due to its conductivity and high affinity for enzyme binding and versatility to prepare porous materials. The enzymes, H2ase for the HER and FDH for the CO2RR, were then immobilised onto the electrode by dropcasting. A three-electrode set-up was used in the chosen electrolyte solution to measure the resultant current density and the solution was stirred to maximise mass transport to the electrode. To demonstrate the reproducibility of the findings at least three repeats were measured for each experiment, each with a newly assembled bioelectrode, in a fresh electrolyte solution.