Glucose oxidation over ultrathin carbon-coated perovskite modified TiO2 nanotube photonic crystals with high-efficiency electron generation and transfer for photoelectrocatalytic hydrogen production

Abstract

Photoelectrocatalytic (PEC) hydrogen production from renewable energy sources (e.g. water, biomass, etc.) has become attractive in the field of renewable energy technology. The potential improvement of hydrogen production processes involves the reduction of the oxidation reaction overpotential, as well as the prohibition of photo-generated electron–hole combination in the photoelectrocatalytic process. Herein, we present high efficiency hydrogen production from PEC glucose oxidation by employing the ultrathin carbon-coated perovskite (Cr-doped SrTiO₃) modified TiO₂ nanotube photonic crystal (C@Cr-SrTiO₃/TiO₂ NTPC) as a photoanode material. The photocurrent density of the C@Cr-SrTiO₃/TiO₂ NTPC photoanode reached as high as 0.43 mA cm⁻² at the bias potential of 0.6 V (vs. SCE) and in glucose electrolyte, which is about 4.8 and 3.3 times higher than that of TiO₂ NTPC and C@Cr-SrTiO₃/TiO₂ NTPC photoanode in pure KOH electrolyte, respectively. The excellent PEC activity and photoelectrochemical performance can be attributed to the less endergonic process of glucose oxidation compared to water oxidation. Additionally, the rational design and fabrication of C@Cr-SrTiO₃/TiO₂ NTPC is favorable towards the high-efficiency generation and transfer of photo-generated electrons, due to the high electrical conductivity and fast transport characteristics of the ultrathin carbon layer, the superior visible light absorption properties of Cr-SrTiO₃ and the independently modulating carrier diffusion length of TiO₂ NTPC. A probable mechanism for PEC hydrogen production from glucose oxidation over the ultrathin carbon-coated heterostructure photoanode is proposed and discussed.