A novel hybrid electrode of zeolitic imidazolate framework–derived carbon encapsulated in reduced‐TiO2 nanotube arrays: Fabrication and photoelectrocatalytic activity

Abstract

Constructing high‐efficient photoelectrodes is one of the promising tasks in photoelectrocatalytic (PEC) technology. Al‐reduced TiO2 nanotube arrays (R‐TNTAs) exhibit distinct improved visible‐light response ability in comparison with traditional TiO2 nanomaterials. In addition, metal–organic framework (MOF)‐derived porous carbon materials possess versatile advantages partly due to preserved geometry configuration of MOF. Inspired by these characteristics, in this work, we synthesized the novel hybrid electrodes of C–N (Zn)@R‐TNTAs through the pyrolysis of ZIF‐8@R‐TNTAs at controlled temperatures, which were pre‐synthesized by coating zeolitic imidazolate frameworks (ZIF‐8) onto R‐TNTAs. The resulting hybrid electrodes were characterized using field‐emission scanning electron microscopy, powder X‐ray diffraction, X‐ray photoelectron spectra, and Fourier‐transform infrared techniques. The EC property and PEC activity of the composite electrodes were also analyzed, and the dependence of these on the pyrolysis temperature was also explored. The results showed that the pyrolyzed carbon materials were uniformly deposited in the inner TiO2 nanotubes and thus effectively enhanced their EC and PEC activities. The best EC and PEC capacities were obtained by C–N (Zn)@R‐TNTAs (600); the maximum photocurrent density was 0.85 mA cm−2, which is ~1.5 times that of single R‐TNTAs; and the maximum H2 evolution rate was 58.83 μmol h−1 cm−2, being ~2.3 times that of R‐TNTAs. In addition, C–N (Zn)@R‐TNTAs (600) exhibited the best PEC activity in the degradation of rhodamine B with excellent catalytic stability. Based on EC analyses, a possible band structure and enhanced PEC mechanism for C–N (Zn)@R‐TNTAs were proposed. There are only a few reports related to reduced TiO2 nanotubes, and this work highlights the ideas of designing the hybrid electrodes based on reduced TNTAs and MOF‐derived carbon materials, which may find broad applications in PC and PEC processes.