Facet-dependent spatial separation of dual cocatalysts on MOF photocatalysts for H2O2 production coupling biomass oxidation with enhanced performance
Ling Yuan, Peiyang Du, Chaoqi Zhang, Yamin Xi, Yingying Zou, Jiaxin Li, Yin Bi, Tong Bao, Chao Liu, Chengzhong Yu
Abstract
Cooperative coupling of photocatalytic two-electron oxygen reduction reaction (2e-ORR) with oxidative organic synthesis holds great promise for sustainable production of valuable chemicals. To achieve high performance, the rational design of photocatalysts with effective electron-hole separation and redox capability is crucial. Herein, a MOF-based photocatalyst with crystal facet-dependent spatial separation of dual cocatalysts is constructed for photocatalytic 2e-ORR coupled with vanillyl alcohol oxidation reaction (VAOR). The facet-dependent growth of reductive Pd and oxidative CoO x cocatalysts respectively on the {100} and {001} facets of MIL-125-NH 2 enables the directional migration of photogenerated carries, facilitating the charge separation for redox reactions. Additionally, the interaction between Pd and MIL-125-NH 2 modulates the Pd sites into electron-sufficient state with upshifted d-band center, promoting the O 2 activation and *OOH intermediate formation. The rationally designed composite photocatalyst delivers an excellent H 2 O 2 yield of 74.8 mM g −1 h −1 and a high vanillic acid production rate of 80.9 mM h −1 g −1 with the conversion and selectivity of 96.8 % and 91.1 %, respectively. • MOF-based photocatalysts with facet-dependent spatial separation of cocatalysts. • Directional migration of photogenerated carries facilitate the charge separation. • Coupling photocatalysis of H 2 O 2 production and vanillyl alcohol oxidation reaction. • Remarkable H 2 O 2 and vanillic acid yields of 74.8 and 80.9 mM h −1 g −1 , respectively.