Jin Lei, Shaaban Ehab, Bamonte Scott, Cintron Daniel, Shuster Seth, Zhang Lei, Li Gonghu, He Jie
Department of Chemistry, University of Connecticut, Storrs, Connecticut 06269, United States.
Department of Chemistry, University of New Hampshire, Durham, New Hampshire 03824, United States.
ACS Appl Mater Interfaces. 2021 Aug 18;13(32):38595-38603. doi: 10.1021/acsami.1c09119. Epub 2021 Aug 9.
Photocatalytic reduction of CO to valuable chemical fuels is of broad interest, given its potential to activate stable greenhouse CO using renewable energy input. We report how to choose the right metal cocatalysts in combination with the surface basicity of TiO to enhance their photocatalytic efficiency for CO photoreduction. Uniform ligand-free metal nanoparticles (NPs) of Ag, Cu, Au, Pd, and Pt, supported on TiO, are active for CO photoreduction using water as an electron donor. The group XI metals show a high selectivity to CO and Ag/TiO is most active to produce CO at a rate of 5.2 μmol g h. The group X metals, e.g., Pd and Pt, mainly generate hydrocarbons including methane and ethane, and Pd/TiO is slightly more active in methane production at a rate of 2.4 μmol g h. The activity of these photocatalysts can be enhanced by varying the surface basicity of TiO with primary amines. However, proton reduction selectivity is greatly enhanced in the presence of amine except amine-modified Ag/TiO, which shows an activity enhancement by 2.4 times solely for CO photoreduction as compared to that without amines without switching its selectivity to proton reduction. Using in situ infrared spectroscopy and CO stripping voltammetry, we demonstrate that the improvement of electron density and the low proton affinity of metal cocatalysts are of key importance in CO photoreduction. As a systematic study, our results provide a guideline on the right choice of metals in combination of the surface functionality to tune the photocatalytic efficiency of supported metal NPs on TiO for selective CO photoreduction.
鉴于光催化将一氧化碳还原为有价值的化学燃料具有利用可再生能源输入来活化稳定的温室气体一氧化碳的潜力，因此该领域备受关注。我们报告了如何结合二氧化钛的表面碱性来选择合适的金属助催化剂，以提高其光催化还原一氧化碳的效率。负载在二氧化钛上的银、铜、金、钯和铂等均匀无配体金属纳米颗粒对以水作为电子供体的一氧化碳光还原具有活性。第11族金属对一氧化碳具有高选择性，银/二氧化钛对一氧化碳的生成最为活跃，生成速率为5.2微摩尔每克每小时。第10族金属，如钯和铂，主要生成包括甲烷和乙烷在内的碳氢化合物，钯/二氧化钛在甲烷生成方面的活性略高，生成速率为2.4微摩尔每克每小时。通过用伯胺改变二氧化钛的表面碱性，可以提高这些光催化剂的活性。然而，除了胺改性的银/二氧化钛外，在胺存在的情况下质子还原选择性大大提高，与没有胺时相比，胺改性的银/二氧化钛仅在一氧化碳光还原方面活性提高了2.4倍，而没有将其选择性切换到质子还原。通过原位红外光谱和一氧化碳脱附伏安法，我们证明了金属助催化剂的电子密度提高和低质子亲和力在一氧化碳光还原中至关重要。作为一项系统研究，我们的结果为结合表面功能正确选择金属提供了指导，以调节负载在二氧化钛上的金属纳米颗粒对一氧化碳选择性光还原的光催化效率。
