Kumar Krishan, Saini Pratibha, Sethi Mukul, Saini Surendra, Gurjar Aditya, Konar Arindam, Dietzek-Ivanšić Benjamin, Weigand Wolfgang, Parewa Vijay
Centre of Advanced Studies, Department of Chemistry, University of Rajasthan, Jaipur 302004 India.
Institute Inorganic and Analytical Chemistry, Friedrich Schiller University Jena, Jena D-07743, Germany.
ACS Appl Mater Interfaces. 2024 Aug 21;16(33):43498-43511. doi: 10.1021/acsami.4c06834. Epub 2024 Aug 8.
Cooperative CO photoreduction with tailored organic synthesis offers a potent avenue for harnessing concurrently generated electrons and holes, facilitating the creation of both solar fuels and specialized chemical compounds. However, controlling the crystallization and morphologies of metal-free molecular nanostructures with exceptional photocatalytic activities toward CO reduction remains a significant challenge. These hurdles encompass insufficient CO activation potential, sluggish multielectron processes, delayed charge-separation kinetics, inadequate storage of long-lived photoexcitons, unfavorable thermodynamic conditions, and the precise control of product selectivity. Here, melem oligomer 2D nanosheets (MNSs) synthesized through pyrolysis are transformed into 1D nanorods (MNRs) at room temperature with the simultaneous engineering of vacancies and morphology. Transient absorption spectral analysis reveals that vacancies in MNRs trap charges, extending charge carrier lifetimes. Additionally, carbon vacancies enhance CO adsorption by increasing amine functional centers. The photocatalytic performance of MNRs for CO reduction coupled with benzyl alcohol oxidation is approximately ten times higher (CHOH and aromatic aldehyde production rate 27 ± 0.5 and 93 ± 0.5 mmol g h, respectively) than for the MNSs (CHOH and aromatic aldehyde production rate 2.9 ± 0.5 and 9 ± 0.5 mmol g h, respectively). The CO reduction pathway involved the carbon-coordinated formyl pathway through the formation of *COOH and *CHO intermediates, as mapped by Fourier-transform infrared spectroscopy. The superior performance of MNRs is attributed to favorable energy-level alignment, enriched amine surfaces, and unique morphology, enhancing solar-to-chemical conversion.
协同的CO光还原与定制有机合成提供了一条有效途径，可同时利用产生的电子和空穴，促进太阳能燃料和特殊化合物的生成。然而，控制对CO还原具有优异光催化活性的无金属分子纳米结构的结晶和形态仍然是一项重大挑战。这些障碍包括CO活化潜力不足、多电子过程缓慢、电荷分离动力学延迟、长寿命光激子存储不足、不利的热力学条件以及产物选择性的精确控制。在此，通过热解合成的蜜勒胺低聚物二维纳米片（MNSs）在室温下转变为一维纳米棒（MNRs），同时对空位和形态进行工程调控。瞬态吸收光谱分析表明，MNRs中的空位捕获电荷，延长了电荷载流子寿命。此外，碳空位通过增加胺官能中心增强了CO吸附。MNRs用于CO还原与苯甲醇氧化耦合的光催化性能（CHOH和芳香醛产率分别为27±0.5和93±0.5 mmol g h）比MNSs（CHOH和芳香醛产率分别为2.9±0.5和9±0.5 mmol g h）高出约十倍。通过傅里叶变换红外光谱绘制的CO还原途径涉及通过形成COOH和CHO中间体的碳配位甲酰途径。MNRs的优异性能归因于有利的能级排列、富集的胺表面和独特的形态，增强了太阳能到化学能的转换。
