Renewable formic acid production from CO2 reduction using green ZnO nanoarchitectures

In order to create an artificial leaf to photoconvert CO2 into fuels, this work describes the syntheses of ZnO with the use of natural and food wastes (nonedible) as biotemplates. The goal was to obtain various nanoarchitectures and produce renewable formic acid from CO2 reduction under visible light. Pea shells, jalapen & SIM;o stems, egg membranes, and shrub leaves were selected as biotemplates for the syntheses of ZnO with different morphologies such as erythrocytes, macarons, hexagonal discs, and spheres, to enhance light harvesting in the visible region. The biotemplates enhanced charge transfer and provided active sites in the zinc interstitial spaces that increased the efficiency of CO2 photoreduction. Formic acid was the main product obtained from CO2 reduction under visible light; the highest yield (185 & mu;mol; S = 95% in 3 h) was reached with a sample prepared by using egg membranes as template, and the catalyst showed remarkable stability over time. Other products with low-carbon contents, e.g., methanol and ethanol, were generated in lower proportions.