Versatile nanobead-scaffolded N-SnO2 mesoporous microspheres: one-step synthesis and superb performance in dye-sensitized solar cell, gas sensor, and photocatalytic degradation of dye

Abstract

Nanobead-scaffolded N-containing SnO₂ mesoporous microspheres (NSMMs) with a high surface area were synthesized in an ethylenediamine (En) solvent system using a one-pot solvothermal route. These spheres are micrometer-sized and consist of packed nanobeads with diameters of ∼10 nm, and possess a specific surface area of 93.64 m² g⁻¹ and main pore sizes of ∼3.56 nm. All structural features of the hierarchically assembled and large well-defined spheres, diameter range, mesoporous properties, higher specific surface areas, high-level donor density, and negative shift of the conduction band could have applications in a variety of areas. As an example, dye-sensitized solar cells (DSSCs) employing NSMM photoanodes exhibit a high overall power conversion efficiency (η) of 2.3%, nearly 116% improvement compared to commercial nanoparticle (CNP) photoanode DSSCs. The distinct photovoltaic behavior of the NSMMs is their large short-circuit current (J_SC = 10.08 mA cm⁻²), which, to the best of our knowledge, is the highest recorded so far among pure SnO₂ photoanodes other than TiO₂ or other modified ones. The NSMMs were also configured as high-performance gas sensors for detecting ethanol gas, exhibiting a remarkable sensitivity and short response/recovery times. Moreover, they were also determined to be high-efficiency photocatalysts for the degradation of rhodamine B solution under simulated sunlight irradiation.