A facile, one-step electroless deposition of NiFeOOH nanosheets onto photoanodes for highly durable and efficient solar water oxidation

Abstract

A low-cost, highly efficient and durable photoelectrochemical (PEC) water-splitting system can be realized through designing a hierarchical core/shell nanostructured photoanode entirely composed of Earth-abundant elements. Herein, we report the rational design of a core/shell nanostructured photoanode with a TiO₂ nanorod (NR) array as the core and a highly active Earth-abundant NiFe oxyhydroxide ((Ni_1−xFe_x)OOH, NiFeOOH) oxygen evolution catalyst (OEC) as the shell for PEC water oxidation. Specifically, the NiFeOOH nanosheets were prepared via a facile, one-step electroless deposition method for a short reaction time of 10 min at room temperature. The TiO₂/NiFeOOH core/shell nanostructured photoanode exhibits an unprecedented enhancement in photocurrent density (3.85 mA cm⁻² at 1.23 V vs. a reversible hydrogen electrode, (RHE)), no decay in photocurrent density over 24 h, and an obvious cathodic onset potential shift of 133 mV compared to the TiO₂ NRs (0.73 mA cm⁻² at 1.23 V vs. RHE). The electron transfer mechanism is discussed through electrochemical impedance spectroscopy studies and calculated band alignments via ultraviolet photoelectron spectroscopy characterization. This work not only suggests a simple, room temperature electroless strategy for integrating Earth-abundant catalysts with photoanodes, but also accelerates the development of rationally designed core/shell photoanodes for efficient and durable solar water oxidation.