Electronic control of catalytic activity of ZnO for higher alcohols synthesis via tailoring Fermi level

Metal doping are essential for electronic modulation of semiconductors, leading to different Fermi level, which determined the surface chemisorption and catalytic properties. Here, ZnO doping with 4 mol% Cu were syn-thesized by four preparation routes, which tuned Cu existing states and Fermi level appearing remarkable im-pacts on the catalytic performance of catalysts. It shows a negative correlation between synthesis of higher alcohols and Fermi level over electronically modified ZnO catalysts, and the lower Fermi level exerted better facilitation for the carbon chain growth. Copper was incorporated into ZnO lattice and existed in the form of isolated Cu2+, which regulated the electronic structure of ZnO with lower Fermi level and boosted the process of catalysts obtaining electrons. Thus, the lower Fermi level promoted the dissociation C-O bond and p-type re-action of forming surface alkyl species, and a higher proportion of straight chain higher alcohols can be achieved via CO or CHxO* inserting into alkyl species. Especially the catalyst prepared by urea hydrolysis with the lowest Fermi level significantly increased the higher alcohols fraction in total alcohol products to 69.9%. For com-parison, the higher Fermi level are unfavorable for p-type reaction, leading to high methanol selectivity. This work provides a new viewpoint for promoting catalytic performance from the perspective of electronic modi-fication of ZnO.

Automated summary

Metal doping is crucial for the electronic modulation of semiconductors, affecting the Fermi level and thus the surface chemisorption and catalytic properties. In this study, ZnO doped with 4 mol% Cu was synthesized using four preparation routes, revealing the significant impact of Cu states and Fermi level on the catalytic performance. Lower Fermi level in the electronically modified ZnO catalysts facilitated higher alcohols synthesis, while higher Fermi level favored methanol selectivity. Copper was incorporated into the ZnO lattice as isolated Cu2+ ions, adjusting the electronic structure and promoting the catalysts' electron acquisition. This work provides a new perspective on promoting catalytic performance through electronic modification of ZnO.