Imparting CO 2 reduction selectivity to ZnGa 2 O 4 photocatalysts by crystallization from hetero nano assembly of amorphous-like metal hydroxides.

Imparting an enhanced CO 2 reduction selectivity to ZnGa 2 O 4 photocatalysts has been demonstrated by controlled crystallization from interdispersed nanoparticles of zinc and gallium hydroxides. The hydroxide precursor in which Zn(ii) and Ga(iii) are homogeneously interdispersed was prepared through an epoxide-driven sol-gel reaction. ZnGa 2 O 4 obtained by a heat-treatment exhibits a higher surface basicity and an enhanced affinity for CO 2 molecules than previously-reported standard ZnGa 2 O 4 . The enhanced affinity for CO 2 molecules of the resultant ZnGa 2 O 4 leads to highly-selective CO evolution in CO 2 photo-reduction with H 2 O reductants. The present scheme is promising to achieve desirable surface chemistry on metal oxide photocatalysts.