Graphitic Layered Structures Enhancing TiNT Catalyst Photo-Electrochemical Behaviour

Abstract

The increasing knowledge in nanoscience and materials technology promoted the development of advanced materials with enhanced and unusual properties suitable for sustainable applications ranging from energy to environmental purposes. Here are presented some results from our current investigations on composite semiconducting materials. The investigated composites have been prepared from different nitrogen precursors and thin films of TiO2 nanotubes. The synergy between hetero-structures based on graphitic-C3N4 and thin films of titania nanotubes obtained by anodisation was studied. The composites have been characterised with several complementary techniques to evidence the relation between photo-behaviour and the composition of the samples. This study allows new insights into the nature of the specific enhanced properties due to this synergy among the two compounds. The g-C3N4/TiNT heterojunctions showed enhanced photo-electrochemical properties observed from the photocurrent measurements. The as-prepared composites have been investigated as cathode materials in the electrocatalytic reduction of oxalic acid (OX), evidencing the capability of tuning the reaction toward glycolic acid with respect to the pristine TiNT array. The observed Faradic efficiency (FE) for the composites follows the trend: TiNT-U6 > TiNT-M6 > TiNT-MU18. TiNT-U6 shows the best performances (FEGC = 63.7%; FEGO = 15.5%; OX conversion = 61. 4%) after 2 h of reaction. The improved photo-electrochemical properties make these materials suitable for H2 production, solar-light-driven water splitting, and CO2 reduction applications.