Morphology-controllable ZnO catalysts enriched with oxygen-vacancies for boosting CO2 electroreduction to CO

Zn-Based Catalysts for Selective and Stable Electrochemical CO2Reduction at High Current Densities

“…The high-resolution spectra (Figure B) for Zn (Zn2p3) also show differences in the binding energies of the characteristic Zn peaks. A difference of 0.7 eV in the position of the Zn-peaks can be observed among our materials, which can be attributed to the distinct difference in morphology, crystallinity, and oxygen vacancies in the materials’ lattice, as observed in previous studies. ,,− The high-resolution O 1s XPS spectra of all allotropes show two deconvoluted peaks at 530 and 531.6 eV, which are attributed to the lattice oxygen and oxygen in the form of surface hydroxy (OH), respectively. The deconvolution of the O-1s peaks reveals different ratios between lattice oxygen and surface −OH.…”

“…37,38 Therefore, it can be concluded that the ZnO-NR presents more O-vacancies than the other ZnObased catalysts. 33 The high-resolution spectra (Figure 2B) for Zn (Zn2p3) also show differences in the binding energies of the characteristic Zn peaks. A difference of 0.7 eV in the position of the Zn-peaks can be observed among our materials, which can be attributed to the distinct difference in morphology, crystallinity, and oxygen vacancies in the materials' lattice, as observed in previous studies.…”

“…These two allotropes exhibit the highest percentage of Zn atoms on their surface in comparison with the rest of the materials. The difference at the surface ratio of Zn:O can be attributed to the lattice vacancies, O-defects, and O-vacancies, different for each allotrope material. , Therefore, it can be concluded that the ZnO-NR presents more O-vacancies than the other ZnO-based catalysts . The high-resolution spectra (Figure B) for Zn (Zn2p3) also show differences in the binding energies of the characteristic Zn peaks.…”

“…22 Recently, ZnO has been also employed as an electrocatalyst for the CO 2 -to-CO conversion, 32 exhibiting promising ECR performance, owing to its crystalline structure and nature of active sites. 29 Further information on the ZnO activity was provided by the work of Zong et al, 33 identifying the oxygen vacancies, in the ZnO structure, to be responsible for enhancing the ECR activity of this material. Nonetheless, only a handful of studies have demonstrated the performance of ZnO catalysts at industrially relevant current densities (>150 mA cm −2 ), 26,33,34 while omitting any reference to catalyst stability at high current densities.…”

“…Further information on the ZnO activity was provided by the work of Zong et al, identifying the oxygen vacancies, in the ZnO structure, to be responsible for enhancing the ECR activity of this material. Nonetheless, only a handful of studies have demonstrated the performance of ZnO catalysts at industrially relevant current densities (>150 mA cm –2 ), ,, while omitting any reference to catalyst stability at high current densities. Previous studies on Zn-based catalysts suggested that these materials exhibit limited stability for current density above 80 mA cm –2 …”