CdTiO3-NPs incorporated TiO2 nanostructure photocatalyst for scavenger-free water splitting under visible radiation

Abstract

Nanofibrous morphology and the doping technique can overcome the problem of electron/hole fast recombination and improve the activity of titanium oxide-based photocatalysts. In this study, nanoparticulate and nanofibrous forms of CdTiO3-incorporated TiO2 were synthesized with different cadmium contents; the morphology and composition were determined by SEM, TEM, EDX, and XRD techniques. The nanomorphology, cadmium content, and reaction temperature of Cd-doped TiO2 nanostructures were found to be strongly affect the hydrogen production rate. Nanofibrous morphology improves the rate of hydrogen evolution by around 10 folds over the rate for nanoparticles due to electron confinement in 0D nanostructures. The average rates of hydrogen production for samples of 0.5 wt.% Cd are 0.7 and 16.5 ml/gcat.min for nanoparticles and nanofibers, respectively. On the other hand, cadmium doping resulted in increasing the hydrogen production rate from 9.6 to 19.7 ml/gcat.min for pristine and Cd-doped (2 wt%) TiO2 nanofibers, respectively. May be the formation of type I heterostructures between the TiO2 matrix and CdTiO3 nanoparticles is the main reason for the observed enhancement of photocatalytic activity due to the strong suppressing of electron/holes recombination process. Consequently, the proposed photocatalyst could be exploited to produce hydrogen from scavenger-free solution. Varying reaction temperature suggests that hydrogen evolution over the proposed catalyst is incompatible with the Arrhenius equation. In particular, reaction temperature was found to have a negative influence on photocatalytic activity. This work shows the prospects for using CdTiO3 as a co-catalyst in photon-induced water splitting and indicates a substantial enhancement in the rate of hydrogen production upon using the proposed photocatalyst in nanofibrous morphology.

TiO2 NPs-immobilized silica granules: New insight for nano catalyst fixation for hydrogen generation and sustained wastewater treatment

“…The energy required to excite electrons from the valence band to the conduction band is determined by the band gap energy of the material. A material with a narrow band gap energy absorbs light of lower energy, while a material with a wide band gap energy absorbs light of higher energy [ 43 , 44 ].…”

“…This hypothesis might be valid for the pure semiconductor. However, in case of composite semiconductor, the interaction between the constituents’ band gaps can result in generating high photocatalytic activity under visible radiation [ 44 , 48 ]. This supposition was experimentally supported as it will be shown in this study.…”

Synergistic doping with Ag, CdO, and ZnO to overcome electron-hole recombination in TiO2 photocatalysis for effective water photo splitting reaction

“…The presence of dopants, the specific reaction mechanism, and complex interplay between charge separation and reaction kinetics likely contribute to this non-Arrhenius behavior. Reactions that involve catalysts or inhibitors may not conform to the Arrhenius equation because the presence of these substances can alter the reaction kinetics in a non-linear manner (Barakat et al, 2020;Erfan et al, 2022).…”