Enhanced photoactivity and conductivity in transparent TiO2 nanocrystals/graphene hybrid anodes

Abstract

An optically transparent and UV-light active anode, characterized by high (photo)conductivity, charge mobility and exciton lifetime, based on graphene, grown by CVD, decorated with colloidal TiO₂ nanocrystals (NCs), has been fabricated, by a direct and facile solution-based procedure. TiO₂ NCs anchor onto graphene by means of π–π stacking interactions occurring between the pyrene-1-butyric acid (PBA) surface coating ligand and the 2-D platform and assemble in a highly interconnected multilayered layout, by means of interligand π–π forces, retaining composition and geometry, along with the graphene structure. Remarkably, the PBA-coated TiO₂ NCs on the graphene increase its electrical conductivity, electroactivity, and capacitive behavior, as well as photoelectrical response under UV-light, resulting in a 50% enhanced photoelectroactivity and a long exciton recombination lifetime. The photoanodes can be integrated into solar cells as optically transparent electrodes, in photodetectors, FETs and (bio)sensors.