Photoelectrochemical Water Oxidation and Longevous Photoelectric Conversion by a Photosystem II Electrode

Abstract The immobilization of natural photosystem II (PSII) enzyme onto an artificial electrode offers an ingenious and promising avenue for semiartificial solar energy conversion. However, this process is significantly limited by the poor stability and the short life of PSII. Here, a new prototype of a semiartificial system is reported by anchoring PSII on polyethylenimine‐coated macroporous carbon electrode with a high load. Good electronic communication is established at the biointerface of this PSII electrode, enabling excellent photoelectrochemical (PEC) water oxidation and lasting electricity generation. The maximum turnover number of 10 200 ± 1380 mol O₂ per mol PSII dimer is obtained in this system at around 10 h before complete deactivation, reaching high current‐to‐O₂ conversion efficiencies. The functions of PSII to release O₂ both in light and dark conditions as well as for H₂O₂ formation are revealed. Under periodic irradiation (AM 1.5G 1 sun), this PSII electrode allows for stable mediated photocurrent output of ≈4.31 µA cm⁻² after five days, which represents the most stable photoelectric performance achieved so far for PSII‐related electrodes.