A TiO₂@MWCNTs nanocomposite photoanode for solar-driven water splitting

Abstract

A TiO2@MWCNTs (multi-wall carbon nanotubes) nanocomposite photoanode is prepared for photoelectrochemical water splitting in this study. The physical and photoelectrochemical properties of the photoanode are characterized using field emission-scanning electron microscopy, transmission electron microscopy, X-ray diffraction, and linear sweep voltammetry. The results show that the TiO2@MWCNTs nanocomposite has an optical bandgap of 2.5 eV, which is a significant improvement in visible-light absorption capability compared to TiO2 (3.14 eV). The cyclic voltammograms show that incorporating TiO2 with the MWCNTs leads to a decrease in the electrical double layer, thereby facilitating the electron transfer rate in the TiO2@MWCNTs electrode. Moreover, the current density of the photoelectrochemical electrode formed by TiO2@MWCNTs under solar irradiation is significantly higher than that prepared by TiO2 (vs Ag/AgCl). The low charge capacity of the TiO2@MWCNTs electrode–electrolyte interface hinders the recombination of the photogenerated electrons and holes, which contributes to the enhancement of the solar-to-hydrogen (STH) conversion efficiency. The average STH conversion efficiency of the TiO2@MWCNTs electrode under solar exposure from 6 AM to 5 PM is 11.1%, 8.88 times higher than that of a TiO2 electrode. The findings suggested TiO2@MWCNTs is a feasible nanomaterial to fabricate the photoanode using photoelectrochemical water splitting under solar irradiation.

Near‐Infrared Active Tri‐nanohybrid for Enhanced Energy Harvesting

“…The series resistance (R s ) value represents the low electrical resistance at the electrolyte junction, while charge transfer resistance (R ct ) is 9.1 kΩ for the PbS‐TiO 2 ‐MWCNT electrode, which is comparatively low for the PbS‐TiO 2 electrode (223 kΩ). The results well agree with the fact that MWCNT introduces significant improvement in the electrical conductivity charge storage capacity at the heterojunction [36] . On the other hand, the electrical double layer capacitance (C EDL ) across the electrolyte‐semiconductor junction is higher (5.9 μF) for the trihybrid photoelectrode, which is 3.5 μF the PbS‐TiO 2 photoanode.…”

“…The results well agree with the fact that MWCNT introduces significant improvement in the electrical conductivity charge storage capacity at the heterojunction. [36] On the other hand, the electrical double layer capacitance (C EDL ) across the electrolyte-semiconductor junction is higher (5.9 μF) for the trihybrid photoelectrode, which is 3.5 μF the PbS-TiO 2 photoanode. The higher C EDL value indicated the prevention of back electron-hole recombination, i. e. accumulation of a larger number of charge carriers across the junction.…”

Nanomaterials for photocatalysis and applications in environmental remediation and renewable energy

“…Moreover, the advantages in the development of advanced materials based on semiconductors (i.e., carbon-modified hexagonal boron nitride (MBN), MgO@g-C3N4, and TiO2@MWCNTs) have indicated a highly efficient photocatalytic performance for phenol removal using a low-power visible LED light source. For NO degradation, a visible light source was used whereas for water splitting natural sunlight was used [ 24 – 26 ]. These results are mentioned as scaling up photocatalytic systems to reach net zero emission goals and the next technology to produce green hydrogen energy [ 14 ].…”