Selective Photo-oxidation of Methane to Methanol with Oxygen over Dual-Cocatalyst-Modified Titanium Dioxide
Selective Photo-oxidation of Methane to Methanol with Oxygen over Dual-Cocatalyst-Modified Titanium Dioxide
复制标题
双助催化剂改性二氧化钛上氧气选择性光氧化甲烷生成甲醇
DOI：
10.1021/acscatal.0c04329
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发表时间：
2020-12-04
期刊：
影响因子：
12.9
通讯作者：
Ye, Jinhua
中科院分区：
文献类型：
--
作者：
Song, Hui;Meng, Xianguang;Ye, Jinhua
CH4与二氧直接选择性氧化制甲醇是现代催化领域的“梦幻反应”，但仍是一个巨大的挑战。在这里，我们报道了负载了纳米金属和氧化钴（CoOx）纳米团簇的TiO2能够在室温光激发下，利用丰富且廉价的O-2作为氧化剂，选择性地催化CH4生成CH3OH。在反应2 h时，CH3OOH和CH3OH的活性最高可达50.8 pmol，选择性为95%。机理研究表明，纳米金属与CoOx的协同作用使其具有良好的活性和选择性。纳米金属通过促进光激发电子的分离和O-2的还原来提高CH4的转化率。CoOx通过抑制高氧化性(OH)- o中心点自由基的形成介导轻度CH4氧化过程，从而进一步将CH3OH氧化为HCHO和CO2，从而保持对氧化产物的高选择性。本研究为设计温和条件下O-2选择性氧化CH4生成CH3OH的高效光催化剂提供了原型。
Direct and selective oxidation of CH4 with dioxygen to methanol is a "dream reaction" in modern catalysis yet remains a great challenge. Here, we report that TiO2 loaded with dual cocatalysts, that is, nanometals and cobalt oxide (CoOx) nanoclusters, is capable of selectively catalyzing CH4 to CH3OH at room temperature under photoexcitation using abundant and inexpensive O-2 as an oxidant. The best activity for the formation of the primary products, CH3OOH and CH3OH, is up to 50.8 pmol for 2 h with 95% selectivity. Mechanistic studies elucidate that the superior activity and selectivity result from the synergistic effect of nanometals and CoOx. Nanometals enhance CH4 conversion by promoting the separation of the photoexcited electron and the reduction of O-2. The CoOx mediates a mild CH4 oxidation process by suppressing the formation of highly oxidative (OH)-O-center dot radicals that can further oxidize CH3OH to HCHO and CO2, thereby preserving a high selectivity toward oxygenated products. This work provides a prototype in designing efficient photocatalysts for selective oxidation of CH4 to CH3OH with O-2 under mild conditions.