Fabrication of a Robust Tantalum Nitride Photoanode from a Flame‐Heating‐Derived Compact Oxide Film

Abstract

Photoelectrochemical (PEC) water splitting provides an attractive way of converting solar energy into hydrogen energy. To make this approach practical, it is crucial to develop strategies that can be used to fabricate efficient photoelectrodes in a scalable manner. Herein, we report a rapid flame heating method to prepare a Ta2O5 precursor film for a Ta3N5 photoanode. By varying the parameters of flame heating, rational control over the physicochemical nature of the Ta2O5 precursor film can be realized. With the following nitridation treatment, the compact precursor film can be transformed into a tight‐knit Ta3N5‐based nitride film which strongly stuck to the underlying conductive Ta substrate. As a result of the close interfacial connections and reasonable conductivity achieved through the manipulation of the duration of flame heating, an enhanced charge‐separation efficiency was obtained for the as‐prepared Ta3N5 photoanode. Furthermore, with the help of a ferrihydrite layer, the photocurrent density for PEC water oxidation on the optimum Ta3N5 photoanode reached circa 3.53 mA cm−2 at 1.23 V vs. RHE, which is among the best values reported for planar Ta3N5‐based photoanodes. This report highlights the advantages of flame heating over traditional heating methods for preparing precursor films for further processing or functionalization.

2D Oxide Nanomaterials to Address the Energy Transition and Catalysis

“…An example is represented by a thin film comprised of an array of vertically ordered TiO 2 nanotubes, modified by supported metal nanoparticles, which were successfully used as advanced photoanodes in new photoelectrocatalytic cells to produce solar fuels . Another example is photoanodes based on tantalum (oxy)nitride nanotube arrays, which can be used in PEC cells for the generation of solar fuels …”