Chitosan coated copper-oxide nano particles: a novel electro-catalyst for CO 2 reduction

We report here a simple one-pot method for the synthesis of copper-oxide based novel film forming electro catalysts for CO2 reduction. Water dispersible chitosan (CS)-CuO/Cu2O (CuxO) nano composites of diameter 10-20 nm were obtained by hydrothermal reactions of CS, CuSO4 center dot 5H(2)O and tartaric acid (TA). Here, TA acts as a multifunctional reagent as de-polymerizer of CS, ionic cross linker of depolymerised CS and complex forming ligand with Cu2+ ions. These CS coated CuxO nanoparticles were characterized by HRTEM, UV-VIS, AFM, FTIR and XPS. An ultra thin film of composite catalyst was deposited onto a Pt electrode by drop cast techniques and applied to study CO2 reduction by cyclic voltammetric techniques. The voltammogram shows a reduction peak at -0.665 V vs. RHE at pH 5.3 with a short hydrogen evolution tail indicating its better performance in terms of retarding the H-2 evolution reaction. This has been explained proposing a model of protonated CS on the electrode surface that repels incoming H+ ions at the electrode-electrolyte interface. This is the first time a film forming copper-oxide based nano composite material for efficient electro-catalytic reduction of CO2 in aqueous solution has been reported.