Boosting CO production from visible-light CO2 photoreduction via defects-induced electronic-structure tuning and reaction-energy optimization on ultrathin carbon nitride,Green Chemistry

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Boosting CO production from visible-light CO2 photoreduction via defects-induced electronic-structure tuning and reaction-energy optimization on ultrathin carbon nitride
Green Chemistry ( IF 9.3 ) Pub Date : 2023-09-27 , DOI: 10.1039/d3gc02371k
Jiaying Li _{1,

2} , Chengxuan He _{1,

2} , Jinlong Wang _{1,

2} , Xiaoyi Gu _{1,

2} , Zehan Zhang _{1,

2} , Huizi Li _{1,

2} , Mingyang Li _{1,

2} , Lingzhi Wang _{1,

2} , Shiqun Wu _{1,

2} , Jinlong Zhang _{1,

2}

Affiliation

Polymeric carbon nitride is a promising photocatalyst for CO₂ reduction; however, its efficiency is limited by the rapid recombination of photogenerated charges and weak CO₂ activation ability. In this study, we present the synthesis of g-C₃N₄ with carbon vacancy and oxygen doping (Vc-OCN) through a facile formaldehyde-assisted thermal polycondensation of molten urea. Comprehensive investigations were carried out and established that the oxygen doping site substituted the 2-coordinated nitrogen site while a carbon vacancy (Vc) was formed at the position of C_3N in the heptazine structure. The incorporation of Vc and oxygen doping could efficiently modify the band structure and electronic structure, leading to enhanced optical absorption and charge separation. In situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) and DFT calculations demonstrated that the Vc-OCN reduced the energy of the rate-determining step of CO₂ conversion, with the Vc serving as the active site for CO₂ activation. Combining thermodynamics and kinetics optimization, Vc-OCN achieved a high CO generation rate of 13.7 μmol g⁻¹ h⁻¹ under visible-light irradiation without the help of any cocatalysts or sacrificial agents, displaying a 7.6-fold improvement over GCN. This study provides a deep understanding of the synergistic effect of doping and vacancies on CO₂ photoreduction and provides novel insights into the design of high-efficiency polymer semiconductors obtained through defects engineering.

中文翻译：

通过缺陷诱导的电子结构调整和超薄氮化碳反应能量优化，促进可见光二氧化碳光还原产生二氧化碳

聚合氮化碳是一种很有前景的CO ₂还原光催化剂；然而，其效率受到光生电荷的快速复合和较弱的CO ₂活化能力的限制。在这项研究中，我们提出了通过熔融尿素的简单甲醛辅助热缩聚合成具有碳空位和氧掺杂的gC ₃ N ₄ (Vc-OCN)。综合研究发现，氧掺杂位点取代了2配位氮位点，同时在C _{3N位置形成了碳空位（Vc）。}在庚嗪结构中。Vc和氧掺杂的结合可以有效地改变能带结构和电子结构，从而增强光学吸收和电荷分离。原位漫反射红外傅里叶变换光谱(DRIFTS)和DFT计算表明，Vc-OCN降低了CO ₂转化速率决定步骤的能量，其中Vc充当CO ₂活化的活性位点。^{结合热力学和动力学优化，Vc-OCN实现了13.7 μmol g −1} h ⁻¹的高CO生成率在可见光照射下，无需任何助催化剂或牺牲剂的帮助，比 GCN 提高了 7.6 倍。_{这项研究提供了对掺杂和空位对CO 2}光还原的协同效应的深入理解，并为通过缺陷工程获得的高效聚合物半导体的设计提供了新颖的见解。

更新日期：2023-09-27

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