第一作者：福州大学 Min Shen
通讯作者：福州大学 邢万东 喻志阳
DOI：https://doi.org/10.1021/acscatal.4c03304
二氧化碳的光还原反应是一种在室温下将太阳能转化为燃料的潜在技术，它加速了碳化合物的回收和转化。然而，基于高活性光催化剂，在原子尺度上解开表面结构的化学环境对产物选择性的影响是具有挑战性的。作者探索了一种硫磺辅助热处理策略，在不添加任何牺牲剂的情况下，将主要产物CH4 （8.2 μmol h-1, 5 mg）变为CO (13.0 μmol h-1, 5 mg)，诱导表面有序线缺陷重构为多边形钨线缺陷。实验结果表明，活性位点为六角形钨线缺陷的表面末端，其中平面内相邻的W原子可以破坏*COOH中间体内部的C-O键，从而促进CO气体的解吸。
Figure 1. (a) Schematic illustration of the modification strategy for the sample showing the surface defect structures changed from the surfaceordered line defect to a novel line defect due to the presence of rotated stacking faults (RSFs) under a sulfur atmosphere within a sealed ampule bottle. (b) In situ XRD patterns of the WO2.9 sample heated from 300 to 600 °C displaying that the single characterized peaks of the WO2.9 photocatalysts transformed into three distinctive peaks in the range of 22°−25°, indicating that the crystal structures transformed into monoclinic WO3 structures. (c) Photoreduction CO2 properties of the as-prepared samples demonstrating that the selectivity of the CO product altered from 5%34 to 90%. Error bars: standard errors.
Figure 2. (a) Typical AC-HAADF image of the WO3−x-RSF500 nanosheets displaying various defect types along the [001] zone axis, including interval tungsten (shown in box (i)), octagonal tungsten (shown in box (ii)), and hexagonal tungsten (shown in box (iii)). The inset is a lowmagnification HAADF image of the WO3−x-RSF500 nanosheets exposed with {002}, {020}, and {200} planes. (b) The strain maps of exx, eyy, and exy for the WO3−x-RSF500 nanosheets performed by GPA showing strong strain distribution around {120} stacking faults. (c) Enlarged ACHAADF images of interval tungsten (left panel), octagonal tungsten (middle panel), and hexagonal tungsten (emphasized by a green frame in the right panel) from the boxes in (a). (d) Relative defect concentrations within the nanosheets.
Figure 3. As-constructed atomic configurations of the (002) surface from the side view (upper panel) and the top view (down panel) for (a) WO3 and (b) WO3−x-RSF500 samples. (c) Surface energies of the hexagonal-tungsten line defects as a function of oxygen chemical potential. (d) Upper panel: the differential charge densities of asconstructed superstructures, demonstrating that CO2 molecules adsorbed on the surface of hexagonal-tungsten line defects via van der Waals forces; Down panel: temperature-programmed desorption spectra of the WO2.9 and WO3−x-RSF500 samples, showing that the adsorption behavior of the CO2 molecules transformed from the chemisorption of the surface-ordered line defect to the physisorption of the RSF-WO1.88 surface configuration of hexagonal-tungsten line defects. The green and red areas represent the electron depletion and accumulation regions with an isosurface value of 0.0005 e/Å3 in the upper panel, respectively.
Figure 4. (a) In situ FT-IR spectra of the WO3−x-RSF500 sample showing the reaction pathways of photoreduction of CO2 to CO products. Gibbs energy diagrams of photoreduction of CO2 over (b) the RSF-WO1.88 surface configuration and (c) the RSF-WO1.88-VO on the diagonal line of hexagonal-tungsten line defects displaying the evolution behavior of the CO2 molecules on the surface of the WO3−x-RSF500 photocatalyst.
Engineering the Atomic Configurations of Surface-Active Sites for Retuning the Photoreduction CO2 Selectivity
https://doi.org/10.1021/acscatal.4c03304
