Two-dimensional TiO2-g-C3N4 with both Ti[sbnd]N and C[sbnd]O bridges with excellent conductivity for synergistic photoelectrocatalytic degradation of bisphenol A

Abstract

TiO2-mediated photoelectrocatalysis is emerging as a promising way to degrade refractory contaminates. Nevertheless, the concrete application of TiO2 is seriously limited because of its poor conductivity, unexpected recombination of photoinduced charges, and broad bandgap (3.2 eV). In this work, two-dimensional (2D) TiO2-g-C3N4 with both TiN and CO bridges is successfully constructed and assembled with carbon fibers to realize efficient photoelectrochemical (PEC) pollutant degradation. Density functional theory (DFT) calculations suggest that the generated interface heterojunction of 2D TiO2-g-C3N4 can provide quick charge separation and transfer via both TiN and CO bridges, resulting in a prepared catalyst that can facilitate the effective separation and transportation of photoinduced electron-hole pairs. In addition, according to electrochemical impedance spectroscopy, the 2D TiO2-g-C3N4 composition with the generated interface heterojunction reduces internal resistance and becomes more conducive to electrocatalysis compared with pure TiO2 or g-C3N4. Using bisphenol A (BPA) as a typical refractory contaminate, the 2D TiO2-g-C3N4/carbon fiber electrode exhibits a higher PEC activity, with reaction rates 1.7, 2.5, and 3 times faster than that of g-C3N4, TiO2, and commercial P25, respectively. Furthermore, the greatest BPA degradation of the PEC system is much higher than the sum of the photocatalytic (PC) and electrocatalytic (EC) systems. Additionally, the enhanced activities of electrocatalysis and photocatalysis for the degradation of BPA is attributed to the collaboration of the interfacial effect and excellent electrical conductivity derived from the 2D structure of the TiO2-g-C3N4 heterojunction. This study proposes a new tactic for the design and construction of photoelectrocatalysts via a synergistic interfacial effect to improve the photocatalytic and electrocatalytic degradation activities for refractory pollutants.