Vertically FeNi layered double hydroxide/TiO2 composite for synergistically enhanced photoelectrochemical water splitting

Non-precious oxygen evolution electrocatalysts have been attracting considerable attention because of their promising potentials in improving the efficiency of water splitting. Among all the candidates, FeNi electrocatalysts show the relatively high electrocatalytic performances, however, it still remains lack for the optimization of their structure and component, and in particular the heterogeneous synergistic effect by integrating with TiO2 photocatalyst. Here, we prepared FeNi electrocatalysts with tunable Fe/Ni composition on TiO2 film by a simple electrodeposition method and studied their microstructure and electrochemical performance. It is found that FeNi3/TiO2 composite composed of vertically layered double hydroxide (LDH), presents ultrathin layer thickness of 280 nm and open-channeled pore architecture, thus contributing to a high density of active sites, promoting the exchange of ions and electrons, and synergistically suppressing the electron-hole recombination. The optimized FeNi3/TiO2 composite exhibits an overpotential of 280 mV at current density of 10 mA/cm(2) and a small Tafel slope of 34 mV/dec. Moreover, the optimized FeNi3/TiO2 composite shows no obvious current drop during the stability test for 8000 s. First-principles calculations demonstrate a synergistic effect of FeNi3/TiO2 composite with the smallest theoretical overpotential based on the density functional theory (DFT) simulations. (C) 2021 Elsevier Ltd. All rights reserved.

Automated summary

The FeNi3/TiO2 composite, consisting of vertically layered double hydroxide, exhibits a high density of active sites, promotes the exchange of ions and electrons, and synergistically suppresses the electron-hole recombination. The optimized composite shows a low overpotential and small Tafel slope, with no obvious current drop during stability testing. First-principles calculations demonstrate a synergistic effect of the FeNi3/TiO2 composite with the smallest theoretical overpotential.