Conductive and Elastic TiO2 Nanofibrous Aerogels: A New Concept toward Self-Supported Electrocatalysts with Superior Activity and Durability.

Abstract

Recently, various titanium dioxide (TiO2 ) nanostructures have received increasing attention in the fields of energy conversion and storage owing to their electrochemical properties. However, these particulate nanomaterials exclusively exist in the powder form, which may cause health risks and environmental hazards. Herein we report a novel, highly elastic bulk form of TiO2 for safe use and easy recycling. Specifically, TiO2 nanofibrous aerogels (NAs) consisting of resiliently bonded, flexible TiO2 nanofibers are constructed, which have an ultralow bulk density, ultrahigh porosity, and excellent elasticity. To promote charge transfer, they are subjected to lithium reduction to generate abundant oxygen vacancies, which can modulate the electronic structure of TiO2 , resulting in a conductivity up to 38.2 mS cm-1 . As a proof-of-concept demonstration, the conductive and elastic TiO2 NAs serve as a new type of self-supported electrocatalyst for ambient nitrogen fixation, achieving an ammonia yield of 4.19×10-10 mol s-1 cm-2 and a Faradaic efficiency of 20.3 %. The origin of the electrocatalytic activity is revealed by DFT calculations.