Optimization of Piezoelectric CO₂ Reduction on ZnO Via α-Fe₂O₃ Decoration for Enhanced Activity and Selectivity

Using piezoelectric catalysis to convert CO₂ and water into fuels or chemicals with waste mechanical energy offers a solution to carbon emissions and energy deficits. The current challenges are the limited efficiency and unpredictable product selectivity. In this study, a novel heterojunction material was prepared by integrating α-Fe₂O₃ nanoparticles with ZnO microrods through a hydrothermal treatment of their mixture. Through careful optimization of the α-Fe₂O₃ content on ZnO surface, the CO₂ reduction rate transitioned from 8.5 μmol·h⁻¹·g⁻¹ (CH₄) and 32.9 μmol·h⁻¹·g⁻¹ (CHOOH) to 118.2 μmol·h⁻¹·g⁻¹ (CH₄) and 18.4 μmol·h⁻¹·g⁻¹ (CHOOH), leading to a substantial enhancement in CH₄ selectivity from 20.6% to 86.5%. Combining CO₂ temperature-programmed desorption, electrochemical analysis, and photoluminescence, it was found that α-Fe₂O₃ plays a crucial role in promoting charge separation and increasing CO₂ adsorption on the catalysts, resulting in a more effective and deeper reduction of CO₂ into CH₄. Our research outlines a strategic methodology for boosting CO₂ reduction efficiency and precisely tailoring the products from piezoelectric catalysis.