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

The simultaneous photocatalytic production of hydrogen (H₂) and hydrogen peroxide (H₂O₂) 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 H₂ and H₂O₂ from water splitting. The optimal catalyst, designated EA-Ni₃, 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 H₂ and 1606.3 µmol g^-1 h^-1 for H₂O₂ 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 H₂O₂. 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) O₂ production alongside H₂ evolution.