Unbiased Photoelectrochemical H ₂ O ₂ Production Using Boron Nitride for Both Photogenerated Hole Extraction and Oxygen Reduction Selectivity Regulation

Abstract Unbiased photoelectrochemical (PEC) H 2 O 2 production offers a sustainable alternative to the energy‐intensive anthraquinone process, yet faces critical bottlenecks: inefficient charge separation, uncontrolled two‐electron oxygen reduction reaction (2e − ORR) pathways, and high‐purity O 2 requirements. Herein, we report an efficient unbiased PEC system for H 2 O 2 production under ambient air. The key innovation involves the strategic implementation of boron nitride (BN) serves a dual role as a charge transfer mediator and ORR pathway modulator. At the photoanode, BN functions as a hole‐extraction layer, because of elevating the valence band position of BiVO 4 (BVO), effectively suppressing interfacial charge recombination between the BVO photoanode and the FeNiOOH cocatalyst, resulting in a photocurrent density achieving 6.08 mA cm −2 at 1.23 V RHE . At the cathode, BN acts as a “reaction helmsman”, tuning the binding energy of the *OOH intermediate and enabling the CoPc + BN to achieve 97% 2e − ORR selectivity at −0.3 V Ag/AgCl . As a result, the integrated system delivers a sustained H 2 O 2 production rate of 1.22 ± 0.14 mM cm −2 h −1 over 16 consecutive cycles. This study provides an innovative solution to address the key challenges in bias‐free H 2 O 2 production.