Heterostructured Sn/SnO_2-x nanotube peapods with a strong plasmonic effect for photoelectrochemical water oxidation

Nonprecious metals with localized surface plasmon resonance (LSPR) are recognized as effective light harvesters owing to their merits of cost-effectiveness and tunable spectral response range. Herein, for the first time, we demonstrate a fascinating nonprecious metallic plasmonic photocatalyst Sn/SnO_2-x with peapod-like hetero-nanostructures fabricated via an electrospinning-hydrogenation process. The hydrogenation gives rise to the simultaneous formation of metallic Sn nanoparticle peas and oxygen vacancies in SnO₂ semiconductors. Metallic Sn generates unprecedented strong LSPR absorption in the visible light region, which significantly enhances the utilization of photon energies in a broad UV-vis region for the peapod-like Sn/SnO_2-x hetero-nanostructure. In addition, the built-in semiconductor-metal Schottky junctions are of great benefit in promoting charge carrier separation and the oxygen vacancies are favorable for accelerating surface catalytic oxygen evolution reaction kinetics. As a result, the peapod-like Sn/SnO_2-x hetero-nanostructure delivers an improved photoelectrochemical performance with a high photocurrent density of 245 μA cm^-2 at 1.23 V versus the reversible hydrogen electrode (RHE), which is seven times higher than that of pristine SnO₂. It is believed that the present work will deepen the comprehensive understanding of the LSPR effect from nonprecious metals and open up new opportunities for other solar energy-related areas.