Towards an integrated solar-to-fuel system: Visible-light driven water oxidation by hole conducting molecular wires in Co ₃O ₄-SiO ₂ core-shell construct

Design of a solar-to-fuel system will require integration of photocatalytic processes into functional nano-assemblies which include light absorbing chromophores, molecular linkers and reaction centres for charge separation, catalytic units for multi-electron redox processes and separation membranes. Here, oligo-para-phenylene vinylene (OPV) molecular wires enabling hole transport from the chromophore to the Co ₃O ₄ water oxidation catalyst is reported. The OPV molecular wires are embedded into a silica shell around Co ₃O ₄ nanoparticles. Co ₃O ₄ nanocrystals with size and shape control were prepared with modified solvothermal routes and tested for water oxidation. Initial transient absorption studies indicates the hole transfer from sensitizer to catalyst. Conformational structure and orientation of the nanoparticle-bound molecular wire were examined by FTIR and FT Raman spectroscopic methods. Kinetics of the competing electron transfer processes is monitored by transient optical absorption spectroscopy and the step scan ATR-FTIR spectroscopy will confirm the transient species during the water oxidation conditions over Co ₃O ₄ catalyst.