Controlled fabrication of hierarchically porous Ti/Sb–SnO2 anode from honeycomb to network structure with high electrocatalytic activity

Abstract

A simple template removal method has been developed for fabrication of hierarchically porous Sb doped SnO₂ electrode with high porosity, effective electroactive sites, and enhanced electrocatalytic efficiency. Two different kinds of hierarchically porous architectures (Ti/Sb–SnO₂-honeycomb and Ti/Sb–SnO₂-network) with remarkable porosity and layer by layer arrangement in multiple directions are fabricated as observed by SEM measurements. EDS confirms the uniform distribution of Sb, Sn and O on substrate surface and the peaks of XRD at 33.9° and 51.8° proves the presences of rutile SnO₂. Linear sweep voltammetry shows the Ti/Sb–SnO₂-honeycomb and Ti/Sb–SnO₂-network possess high OEP value upto 2.60 V, and 2.76 V. By analyzing CV curves, the recorded total voltammetric charge for hierarchically porous electrodes is boosted upto 7.46 mC cm⁻² and 11.96 mC cm⁻², compared to the conventional one (3.0 mC cm⁻²), which indicates the significant enhancement in electrochemical active sites. The electrocatalytic efficiency is explored by degradation of Rhodamine B under different parameters (pH, current density, and concentration). The reaction rates for Ti/Sb–SnO₂-honeycomb and Ti/Sb–SnO₂-network are 9.2 × 10⁻² min⁻¹ and 19.7 × 10⁻² min⁻¹, respectively, which are 2.2 and 4.7 times higher than conventional one (k = 4.2 × 10⁻² min⁻¹). Further mechanistic study suggests that more electroactive sites provided by hierarchically porous electrodes lead to accelerate HO˙ generation and the channels of porous structure significantly promotes the adsorption and diffusion of pollutant molecules.