Efficient Bipolar Hydrogen Peroxide Production Through Photoelectrochemistry

Hydrogen peroxide (H 2 O 2 ) is a crucial environmentally benign oxidant. Photoanodes in bias‐free photoelectrochemical (PEC) systems suffer from poor H 2 O 2 selectivity at low potentials, limiting the efficiency of bipolar H 2 O 2 production. Herein, we report a rare‐earth ytterbium oxide (YbO x ) modified BiVO 4 /WO 3 photoanode for efficient PEC water oxidation to H 2 O 2 . The optimized photoanode achieves a photocurrent density of 4.83 mA cm −2 at 1.23 V RHE , an H 2 O 2 Faradaic efficiency (FE) of over 80% across the potential range of 0.6–1.8 V RHE , and a peak FE of 90.4% at 1.6 V RHE . Yb 3+ Lewis acid sites suppress the competitive four‐electron oxygen evolution reaction by forming Yb‐hydroxyl complexes, while YbO x enhances charge transfer and reduces interfacial resistance. Importantly, when coupled with a FeZnWMnYb high‐entropy amorphous oxide cathode for the two‐electron oxygen reduction reaction, the bias‐free tandem cell achieves ∼160% bipolar H 2 O 2 FE. Scaling the photoelectrode to 20 cm 2 under 0.7 suns illumination yields an H 2 O 2 production rate of 3.03 mmol L −1 h −1 . This work demonstrates a viable strategy for large‐scale solar‐driven H 2 O 2 synthesis for environmental applications.