Ag/Pd bimetallic nanoparticle-loaded Zr-MOF: an efficacious visible-light-responsive photocatalyst for H2O2 and H2 production

Photocatalytic production of H2O2 and H-2 holds promise for conquering the impending energy crisis. In order to accomplish this goal, the photocatalysts must be robust and effective enough to harvest photons from a wide solar spectrum as well as having a high rate of exciton antirecombination. Low visible light absorption and fast recombination of exciton pairs are two major setbacks encountered in pristine MOF-based photocatalysts. Herein, the MOF UiO-66-NH2 modified with noble bimetallic nanoparticles (Ag/Pd) was synthesized via a facile adsorption-reduction technique and utilized for effective photocatalytic H2O2 and H-2 production. The composite (1 : 2) Ag/Pd@UiO-66-NH2 displayed a H2O2 production rate of 39.4 mu mol h(-1) in an O-2-saturated environment in the presence of IPA and water under visible light illumination, which is almost four-fold more than that of the pristine UiO-66-NH2 MOF and twofold greater than those of the monometallic counterparts (Ag@MOF or Pd@MOF). Moreover, the photocatalytic H-2 evolution of the prepared materials was studied and a similar trend was observed in which the composite (1 : 2) Ag/Pd@UiO-66-NH2 showed the highest H-2 evolution capacity of 448.2 mu mol h(-1). The enhanced photocatalytic performance of the Ag/Pd@MOF composite can be attributed to its ability to suppress exciton recombination, superior photon reception, and fast charge transfer. Mechanistically the transfer of photogenerated electrons from the UiO-66-NH2 surface to the bimetallic component was promoted through the LSPR effect of Ag and this is further enhanced by the Pd support. The electron-trapping capacity of the bimetallic nanoparticle (NP)-based co-catalyst enhances the overall reaction mechanism by giving highly surface active sites on the surface for the photocatalytic production of H2O2 and H-2 as a sustainable means of green energy production.