Band‐Gap Narrowing of Highly Stable Heterogeneous ZrO2–ZnO Nanocomposites for the Reductive Amination of Carbonyl Compounds with Formic Acid and Triethylamine

The band gap of a material can be affected by factors such as size, doping materials, and oxygen vacancies. The decrease in band gap and change in state of ZrO2 with the addition of ZnO indicates interfacial interactions between ZrO2 and ZnO in the nanocomposites (NCs), which is further confirmed by the observed shift of the peaks in the Raman spectra. Heterobimetallic ZrO2–ZnO NCs were synthesized through a sustainable green approach by using sucrose isolated from Angelica gigas Nakai root extract. The highly stable NCs displayed excellent catalytic activity for reductive amination of carbonyl compounds utilizing HCO2H/(CH3CH2)3N as a hydrogen source. The high catalytic performance of the NCs was closely correlated with the narrow band gap and synergistic effect of ZrO2 with ZnO in the NCs.