Exploiting the synergistic catalytic effects of CoPi nanostructures on Zr‐doped highly ordered TiO ₂ nanotubes for efficient solar water oxidation

Abstract

Photoelectrochemical (PEC) catalysis offers promising strategies for sustainable development. This study demonstrated the synergistic catalytic behavior of ZrO 2 and a cobalt phosphate on anodized TiO 2 nanotubes (TNTs), which significantly enhanced the PEC performance for visible-light-driven water splitting reactions. The sequential addition of ZrO 2 /CoPi-decorated TNTs was performed via electrodeposition and photoassisted electrodeposition. The substitution of Zr 4+ by Ti 4 can lead to the creation of oxygen vacancies, enabling electron trapping, reducing charge recombination, and thereby enhancing the charge transfer efficiency. Further, in the case of TNTs/ZrO 2 /CoPi photoanode, the CoPi WOC functioned as a hole-transfer relay to promote the water-splitting reaction. Specifically, incorporating ZrO 2 /CoPi rushes the surface reaction kinetics of TNTs and considerably improves charge transfer efficiency (η CT = 90%), photocurrent density (0.86 mA/cm 2 at 1.23 V RHE ) and durability were obtained. Further, the mechanistic examination by impedance measurements showed the enhanced charge transfer, and surface conductivity for prepared materials. The proposed method can be widely used to develop electrodes made of other materials to produce solar fuels.

Enhanced Electrocatalytic Oxygen Reduction Reaction of TiO2 Nanotubes by Combining Surface Oxygen Vacancy Engineering and Zr Doping

“…This work and our previous studies [ 33 , 47 , 48 ] confirm the fact that the vacuum annealing process is more responsible for enhanced electrochemical activity than Zr doping. In Figure 9 , different LSV diagrams from Figure 4 and Figure 5 are presented for different comparisons that can shed light on the weight of each of the two parameters.…”

“…The electrochemical tests also confirm the importance of the vacuum annealing effect on Zr-doped TNTs. Overall, the Zr doping and vacuum annealing of TNTs proved to be a successful combination for increasing ORR activity, in agreement with the reported literature on other electrochemical systems [33,47,48].…”

“…The electrochemical tests also confirm the importance of the vacuum annealing effect on Zr-doped TNTs. Overall, the Zr doping and vacuum annealing of TNTs proved to be a successful combination for increasing ORR activity, in agreement with the reported literature on other electrochemical systems [33,47,48]. The origin of the two cathodic peaks, and if they are directly related to oxygen reduction at the surface of the champion Zr:TNT-Vac sample, can be investigated by changing the gas purging environment during LSV measurements.…”

“…Compared with TNT-air, the synergetic effect of Zr doping and vacuum annealing showed a 232 mV positive potential shift. Therefore, vacuum annealing reduces TNT potential more This work and our previous studies [33,47,48] confirm the fact that the vacuum annealing process is more responsible for enhanced electrochemical activity than Zr doping. In Figure 9, different LSV diagrams from Figures 4 and 5 are presented for different comparisons that can shed light on the weight of each of the two parameters.…”

Boosting the Photoelectrochemical Water Oxidation Performance of TiO2 Nanotubes by Surface Modification Using Silver Phosphate

“…Interestingly, the obtained Mott-Schottky plots of the pure TNTs and the composite TNTs/Ag 3 PO 4 array films revealed a positive slope, as expected for n-type semiconductor electrodes. Obviously, the acquired curves remarkably validated that the fabricated composite array films had a lesser slope than their pure TNTs, indicating the enriched carrier density and also the improve conductivity features of the former [53]. In particular, the assessed carrier density of the fabricated TNTs/Ag 3 PO 4 was 2.8 × 10 19 cm −3 , greater than that of the pure TNTs electrodes (7.90 × 10 18 cm −3 ).…”