Development of a Core–Shell Heterojunction\nTa₃N₅‑Nanorods/BaTaO₂N Photoanode\nfor Solar Water Splitting

Abstract

Heterostructure-based\nphotoanodes have been investigated to enhance\nlight absorption and promote the generation and extraction of charge\ncarriers for efficient solar-to-hydrogen energy conversion. Oxy­(nitride)\nsemiconducting materials are promising candidates to harvest the visible\nsolar spectrum; however, the realization of stable and efficient oxy­(nitride)\nheterostructure-based photoanodes remains a challenge. Here, we demonstrate\na core–shell heterojunction photoanode of Ta₃N₅-nanorods/BaTaO₂N that is obtained by combining\nglancing angle deposition and dip coating techniques. The heterojunction\nphotoanode homogeneously covered by a FeNiO_<i>x</i> cocatalyst (Ta₃N₅-NRs/BaTaO₂N/FeNiO_<i>x</i>) generates a stable photocurrent\nof ∼4.5 mA cm^–2 at 1.23 V_RHE under\nsimulated AM 1.5G sunlight. The stoichiometric evolution of O₂ and H₂ from water occurs steadily over an hour\nwhen the covered heterojunction photoanode is connected to a Pt counter\nelectrode with faradaic efficiencies of 90%–95%. This work\nmay open a new path to fabricating efficient and stable oxy­(nitride)\nphotoactive materials for solar energy conversion.