Band Position-Independent Piezo-Electrocatalysis for Ultrahigh CO₂ Conversion

Piezo-electrocatalysis as an emerging mechano-to-chemistry energy conversion technique opens multiple innovative opportunities and draws great interest over the past decade. However, the two potential mechanisms in piezo-electrocatalysis, i.e., screening charge effect and energy band theory, generally coexist in the most piezoelectrics, making the essential mechanism remain controversial. Here, for the first time, the two mechanisms in piezo-electrocatalytic CO₂ reduction reaction (PECRR) is distinguished through a narrow-bandgap piezo-electrocatalyst strategy using MoS₂ nanoflakes as demo. With conduction band of -0.12 eV, the MoS₂ nanoflakes are unsatisfied for CO₂ -to-CO redox potential of -0.53 eV, yet they achieve an ultrahigh CO yield of ≈543.1 µmol g^-1  h^-1 in PECRR. Potential band position shifts under vibration are still unsatisfied with CO₂ -to-CO potential verified by theoretical investigation and piezo-photocatalytic experiment, further indicating that the mechanism of piezo-electrocatalysis is independent of band position. Besides, MoS₂ nanoflakes exhibit unexpected intense "breathing" effect under vibration and enable the naked-eye-visible inhalation of CO₂ gas, independently achieving the complete carbon cycle chain from CO₂ capture to conversion. The CO₂ inhalation and conversion processes in PECRR are revealed by a self-designed in situ reaction cell. This work brings new insights into the essential mechanism and surface reaction evolution of piezo-electrocatalysis.