Water Splitting for Hydrogen and Hydrogen Peroxide Co‐Production by Carbon‐Based Photocatalyst with Two Types Active Sites

Abstract The simultaneous photocatalytic production of hydrogen (H ₂ ) and hydrogen peroxide (H ₂ O ₂ ) from water is highly desirable for its valuable products and simple separation, yet it remains a formidable challenge. Here, a new carbon‐based photocatalyst is reported that exhibits photocatalytic activity for the co‐production of H ₂ and H ₂ O ₂ from water splitting. The optimal catalyst, designated EA‐Ni ₃ , contains two types of active sites, namely, the conjugated carbonyl oxygen group coordinated with the Nickel (Ni) atom (O _α site) and the pure conjugated carbonyl oxygen group (O _β site). It achieves production rates of 20.3 µmol g ⁻¹ h ⁻¹ for H ₂ and 1606.3 µmol g ⁻¹ h ⁻¹ for H ₂ O ₂ under ambient conditions without any sacrificial agents. Through electrochemical tests, in situ characterization, and theoretical calculations, it has been elucidated that the O _β site acts as a cascade reaction site for the two‐electron water oxidation reaction (2e ⁻ WOR) and the oxygen reduction reaction (ORR) to produce H ₂ O ₂ . For the O _α site, the Ni atom alters the charge density on the carbonyl oxygen, enabling the O _α site to serve as a cascade reaction site for the four‐electron water oxidation reaction (4e ⁻ WOR) O ₂ production alongside H ₂ evolution.