Stabilizing Co nanoparticles for CO ₂ hydrogenation by lattice-matching confinement in ZnO interlayers

Confining active nanoparticles within specific nanoscale spaces is a promising strategy to improve the catalytic activity, selectivity and stability of catalysts. In this study, we present a lattice-matching approach to confine Co particles within ZnO layers (ZnO/Co/ZnO) for CO₂ hydrogenation, a critical and challenging reaction in the field of CO₂ utilization and energy production. XRD patterns reveal that the lattice mismatch between ZnO and hexagonal wurtzite CoO (w-CoO) is only 0.18%, facilitating the epitaxial growth of w-CoO on the ZnO surface, or vice versa. This minimal mismatch enables the successful confinement of w-CoO within the ZnO interlayers. This advanced methodology can also be adapted to diverse ZnO morphologies, allowing the optimization of the confined catalyst microstructure. Significantly, when Co particles are confined within the interlayer of ZnO, they exhibit excellent catalytic activity, achieving a rate of 15.8 μ<inline-formula id="Z-20250221160934"> <math id="mathml_Z-20250221160934" display="inline" overflow="scroll"><msub><mrow class="MJX-TeXAtom-ORD"><mtext>mol</mtext></mrow><mrow class="MJX-TeXAtom-ORD"><msub><mrow class="MJX-TeXAtom-ORD"><mtext>CO</mtext></mrow><mrow class="MJX-TeXAtom-ORD"><mtext>2</mtext></mrow></msub></mrow></msub><mo>⋅</mo><msubsup><mrow class="MJX-TeXAtom-ORD"><mtext>g</mtext></mrow><mrow class="MJX-TeXAtom-ORD"><mrow class="MJX-TeXAtom-ORD"><mtext>Co</mtext></mrow></mrow><mrow class="MJX-TeXAtom-ORD"><mo>−</mo><mrow class="MJX-TeXAtom-ORD"><mtext>1</mtext></mrow></mrow></msubsup><mo>⋅</mo><msup><mrow class="MJX-TeXAtom-ORD"><mtext>s</mtext></mrow><mrow class="MJX-TeXAtom-ORD"><mo>−</mo><mrow class="MJX-TeXAtom-ORD"><mtext>1</mtext></mrow></mrow></msup></math></inline-formula> for CO₂ hydrogenation reaction. Moreover, no appreciable deactivation was observed even after 700 h of continuous operation. These results introduce a novel approach for the development of confined catalysts with enhanced activity and long-term stability.