Enhanced Photoelectrocatalytic Activities for CH3 OH-to-HCHO Conversion on Fe2 O3 /MoO3 : Fe-O-Mo Covalency Dominates the Intrinsic Activity.

The catalytic conversion of alcohols under mild conditions is a great challenge because it is constrained by low selectivity and low activity. Herein, we demonstrate a hollow nanotube Fe2 O3 /MoO3 heterojunction (FeMo-2) for the photoelectrocatalytic conversion of small-molecule alcohols. Experimental and theoretical analyses reveal that the optical carrier transfer rate is enhanced by constructing interfacial internal electric fields and Fe-O-Mo charge transfer channels. For the formox process, heterojunctions possess superior HCHO-selective reaction paths and free energy transitions, optimizing the selectivity of HCHO and enhancing the reactivity. FeMo-2 shows a greatly improved performance compared to single Fe2 O3 ; the photocurrent density of FeMo-2 reaches 0.66 mA cm-2 , which is 3.88 times that of Fe2 O3 (0.17 mA cm-2 ), and the Faraday efficiency of the CH3 OH-to-HCHO conversion is 95.7 %. This work may deepen our understanding of interfacial charge separation and has potential for the production of HCHO and for conversion reactions of other small-molecule alcohols at cryogenic temperatures.