Surface‐Passivated Vertically Oriented Sb<sub>2</sub>S<sub>3</sub> Nanorods Photoanode Enabling Efficient Unbiased Solar Fuel Production

Abstract

<jats:title>Abstract</jats:title><jats:p>The lack of highly efficient photoanodes presents a significant challenge to implementing the promising strategy of unbiased solar‐to‐fuel conversion. To achieve high‐performance photoanodes, improving their light harvesting and charge separation/injection capabilities is indispensable. Herein, solution‐processed vertically oriented Sb<jats:sub>2</jats:sub>S<jats:sub>3</jats:sub> nanorod arrays on substrate are obtained via a Au seed layer, resulting in improved optoelectronic properties (due to the light scattering effect) and favorable crystallographic orientation of the 1D nanostructure. Moreover, the (NH<jats:sub>4</jats:sub>)<jats:sub>2</jats:sub>WS<jats:sub>4</jats:sub> treatment caps the surface of the nanorods with an amorphous WS<jats:italic><jats:sub>x</jats:sub></jats:italic> layer and passivates the sulfur vacancy of Sb<jats:sub>2</jats:sub>S<jats:sub>3</jats:sub>, resulting in boosted charge extraction to the reactants. The resulting photoanode is employed to drive an iodide oxidation reaction (IOR), which is a prominent alternative to sluggish water oxidation reactions, exhibiting a high photocurrent density of 13 mA cm<jats:sup>−2</jats:sup> at 0.6 V versus the reversible hydrogen electrode. Subsequently, an unassisted hydrogen generation device is demonstrated by combining an Sb<jats:sub>2</jats:sub>S<jats:sub>3</jats:sub> nanorod array‐based photoanode for IOR and a perovskite‐based photocathode for the hydrogen evolution reaction, achieving an efficient hydrogen production current density of 5.7 mA cm<jats:sup>−2</jats:sup> without any external bias.</jats:p>