Surface‐Passivated Vertically Oriented Sb2S3 Nanorods Photoanode Enabling Efficient Unbiased Solar Fuel Production.

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 Sb2S3 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 (NH4)2WS4 treatment caps the surface of the nanorods with an amorphous WSx layer and passivates the sulfur vacancy of Sb2S3, 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−2 at 0.6 V versus the reversible hydrogen electrode. Subsequently, an unassisted hydrogen generation device is demonstrated by combining an Sb2S3 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−2 without any external bias. [ABSTRACT FROM AUTHOR]