With the introduction of Ga3+ into Cu/ZnO catalyst precursors, a series of catalysts have been prepared using a simple co-precipitation method and tested as catalysts for the synthesis of methanol from CO2 hydrogenation. It is found that the presence of a small amount of Ga3+ can facilitate thermal deep reduction of ZnO support to Zn atoms under hydrogen prior to catalysis; hence, a highly active CuZn bimetallic nanoparticle offering catalytic sites is generated. The effect of Ga3+ incorporation is attributed to the formation of Ga-containing spine], ZnGa2O4 structure, which creates electronic heterojunction with excess ZnO phase to account for the facilitated reduction of Zn2+ to Zn-0 to form CuZn when in contact with Cu nanoparticle. A correlation between Zn-0 concentration in the CuZn alloy nanoparticle to the catalytic performance can thus be clearly demonstrated, which shows CO2 conversion and methanol selectivity can be significantly improved by increasing the Zn-0 content in these hetero-junctioned catalysts. (C) 2016 Elsevier Inc. All rights reserved.