Atom-passivated GeC nanosheets for photocatalytic overall water splitting with high solar-to-hydrogen conversion efficiency

Abstract

The high solar-to-hydrogen conversion efficiency (ηSTH′) of the photocatalytic overall water splitting can be achieved by well-designed nanostructures. Here, we describe that the high ηSTH′ of hydrogen evolution reaction (HER) can be achieved on the atom-passivated GeC nanosheets with the irradiation of sunlight. The suitable geometrical structures of eight GeC nanosheets passivated by different atoms are identified by systematic optimizations, and the stabilities are confirmed by ab initio molecular dynamics simulations. According to the anisotropic vacuum levels induced by the passivated atoms, 16 photocatalytic overall water splitting schemes are constructed for each nanosheet, and the qualified ones for HER and oxidation evolution reaction (OER) are recognized by the redox potentials and the charge density distributions of the band alignments. Then, the ηSTH′s are evaluated with bandgaps and overpotentials. Remarkably, a maximum ηSTH′ of 16.41% can be achieved for the F-GeC-SeF nanosheet, and a higher 20.74% is observed at 3% tensile strain. The optical absorption, mobility, and Gibbs free energy changes in HER and OER are calculated to understand the photocatalytic performances driven by the newfound nanosheets. All the results support that the atoms-passivated GeC nanosheets are the potential candidates for developing sunlight photocatalysts for producing hydrogen from overall water splitting.