MnO₂ Nanowires Decorated with Au Nanoparticles\nfor Plasmon-Enhanced Electrocatalytic Detection of H₂O₂

Abstract

MnO₂ is a cheap and versatile\nmaterial, being able to\nact as a catalyst for different electrochemical reactions. The addition\nof small amounts of Au nanoparticles (NPs) enables the possibility\nto explore the localized surface plasmon resonance (LSPR) effect to\nimprove the photocatalytic properties of MnO₂. The LSPR\neffect can accelerate several reactions under visible light irradiation,\nimproving the charge separation and light harvesting properties of\nsemiconductors. Here, by employing MnO₂ nanowires decorated\nwith Au NPs (MnO₂–Au), we demonstrated that MnO₂ catalytic activity can be greatly improved by the LSPR in\na hybrid system. The catalytic properties of the semiconductor were\ndemonstrated for the H₂O₂ oxidation as a model\nreaction. A clear increase in the current of H₂O₂ oxidation was verified for gold decorated nanowires under visible\nlight irradiation, with an increase of 116% in the sensitivity compared\nwith dark conditions. Mechanistic analysis indicates that the increased\nperformance was related to a more efficient charge separation by plasmonic\ngenerated hot electrons and holes. Moreover, we demonstrated that\nthe thermal effect had no significant contribution to the increase\nin activity observed, as it was verified no expressive increase in\ntemperature under light irradiation with a thermal camera. We believe\nthe results reported herein provide an approach to achieve improved\nlight harvesting and performance in the visible range of the spectrum\nfor semiconductors, inspiring the use of plasmonic heterostructures\ntoward electrocatalysis.