Green hydrogen production by photocatalytic direct dehydrogenation of methanol on CuPt/TiO2

Abstract

To obtain H2 from methanol under zero carbon emission is a tough challenge. Herein, photocatalytic direct dehydrogenation of methanol to H2 and methyl formate on titania, specifically focusing on the {101}, {100}, and {001} facets supported with CuPt nanoparticles, is investigated by experiment and density functional theory. Our findings reveal that the {100} facets exhibit favorable methanol adsorption characteristics, attributed to their lowest adsorption energy, followed by the {001} and {101} facets. Moreover, methanol adsorbed on the {100} facet readily undergoes conversion to methoxy due to the weakened O-H bond. The formation of surface TiOx resulting from the strong interaction between the support and CuPt nanoparticles proves advantageous for methanol adsorption and dissociation, owing to its low adsorption energy and weakened O-H bond. The pathway from methoxy to methyl formate involves three sequential steps: (1) *CH3O → *CH2O + *H; (2) *CH2O → *CHO + *H; (3) *CH3O + *CHO → HCOOCH3, as opposed to a one-step route of *CH3O + *CH2O → *HCOOCH3 + *H. Remarkably, the {101} facet exhibits the highest catalytic activity among all surfaces, as evidenced by its lowest energy barrier and potential energy at each transition state.