Z-Scheme Hydrothermal Carbonaceous Carbon/MoO 2 Heterojunction via One-Pot Synthesis for Photocatalytic H 2 O 2 Production from Seawater

Utilizing inexhaustible seawater for the photocatalytic H 2 O 2 production presents a significant challenge but offers a promising path toward sustainable energy. Herein, a Z-scheme MoO 2 -hydrothermal carbonaceous carbon (HTC) heterostructure was developed by a facile one-pot hydrothermal strategy for photocatalytic H 2 O 2 production from seawater. The one-pot synthesis enables intimate MoO 2 /HTC interfacial contact, which creates efficient charge migration pathways and significantly enhances charge separation. The optimal MoO 2 /HTC material yielded a remarkable H 2 O 2 production rate of 1078 μmol·g –1 ·h –1 in natural seawater (859 μmol·g –1 ·h –1 in ultrapure water). This superior activity arises from efficient charge separation and the robust redox capability of the Z-scheme heterostructure, as well as the favorable effects of certain ions (Mg 2+, Na +, SO 4 2– ) in seawater on charge transfer. Ultraviolet photoelectron spectroscopy (UPS) characterization confirmed the formation of an internal electric field, which is induced by the Fermi level difference between the two materials. Moreover, zeta potential analysis and coexistence ion experiments demonstrated that MoO 2 loading on HTC enhanced H 2 O 2 photoproduction in seawater, which is attributed to the improved utilization efficiency of • O 2 – . Our findings provide crucial mechanistic insights that set the stage for designing next-generation Z-scheme catalysts capable of efficiently producing H 2 O 2 directly from seawater.