RuIII-edta (edta4? = ethylenediaminetetraacetate) mediated photocatalytic conversion of bicarbonate to formate over visible light irradiated non-metal doped TiO2 semiconductor photocatalysts

摘要

Reported in this paper is the first example of a ruthenium( III ) complex, [Ru ~(III) (edta)] (edta ~(4?) = ethylenediaminetetraacetate), that catalyzes the conversion of bicarbonate to formate selectively over a visible light irradiated surface of carbon, nitrogen and sulfur doped TiO _(2) (represented as C–TiO _(2) , N–TiO _(2) and S–TiO _(2) , respectively) semiconductor photocatalyst particles. Formation of formate, the only reduction product, was identified by ~(13) C NMR analysis of the reaction mixture. Based on the experimental findings a working mechanism involving activation of bicarbonate (HCO _(3) ~(?) ) through the formation of a [Ru ~(III) (edta)(HCO _(3) )] ~(2?) intermediate complex followed by the photochemical reduction of the coordinated bicarbonate to produce formate at the surface of non-metal (C, N, S) doped TiO _(2) semiconductor particles is proposed. The efficacy of bicarbonate reduction over such photocatalysts decreased in the following order C–TiO _(2) > N–TiO _(2) > S–TiO _(2) .