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1. Dual Functions of CO 2 Molecular Activation and 4 f Levels as Electron Transport Bridge in Dysprosium Single Atom Composite Photocatalysts with Enhanced Visible‐Light Photoactivities

   https://doi.org/10.1002/adfm.202104976  

   Zhao, Yue ; Han, Zhendong ; Gao, Guoyang ; Zhang, Wanying ; Qu, Yang ; Zhu, Hongyang ; Zhu, Peifen ; Wang, Guofeng ( July 2021 , Advanced Functional Materials)

   The effect of rare earth (RE) single atoms on photocatalytic activity is very complex due to its special electronic configuration, which leads to few reports on the RE single atoms. Here, Dy³⁺single atom composite photocatalysts are successfully constructed based on both the special role of Dy³⁺and the special advantages of CdS/g‐C₃N₄heterojunction in the field of photocatalysis. The results show that an efficient way of electron transfer is provided to promote charge separation, and the dual functions of CO₂molecular activation of rare‐earth single atom and 4flevels as electron transport bridge are fully exploited. It is exciting that under visible‐light irradiation, the catalytic performance of CdS:Dy³⁺/g‐C₃N₄is≈6.9 times higher than that of pure g‐C₃N₄. The catalytic performance of CdS:Dy³⁺and CdS:Dy³⁺/g‐C₃N₄are≈7 and≈13.7 times higher than those of pure CdS, respectively. Besides, not all RE ions are suitable for charge transfer bridges, which is not only related to the 4flevels of RE ions but also related to the bandgap structure of CdS and g‐C₃N₄. The pattern of combining single‐atom catalysis and heterojunction opens up new methods for enhancing photocatalytic activity.

    

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2. Effect of Carbon Doping on CO 2 ‐Reduction Activity of Single Cobalt Sites in Graphitic Carbon Nitride

   https://doi.org/10.1002/cnma.202100164  

   Huang, Peipei ; Huang, Jiahao ; Li, Junying ; Zhang, Lei ; He, Jie ; Caputo, Christine A. ; Frenkel, Anatoly I. ; Li, Gonghu ( June 2021 , ChemNanoMat)

   Single‐atom catalysts have demonstrated interesting activity in a variety of applications. In this study, we prepared single Co²⁺sites on graphitic carbon nitride (C₃N₄), which was doped with carbon for enhanced activity in visible‐light CO₂reduction. The synthesized materials were characterized with a variety of techniques, including microscopy, X‐ray powder diffraction, UV‐vis spectroscopy, infrared spectroscopy, photoluminescence spectroscopy, and X‐ray absorption spectroscopy. Doping C₃N₄with carbon was found to have profound effect on the photocatalytic activity of the single Co²⁺sites. At relatively low levels, carbon doping enhanced the photoresponse of C₃N₄in the visible region and improved charge separation upon photoactivation, thereby enhancing the photocatalytic activity. High levels of carbon doping were found to be detrimental to the photocatalytic activity of the single Co²⁺sites by altering the structure of C₃N₄and generating defect sites responsible for charge recombination.

    

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3. Heterogeneous In/Mo cooperative bandgap engineering for promoting visible-light-driven CO 2 photoreduction

   https://doi.org/10.1039/D2TA02904A  

   Gao, Guoyang ; Wang, Qiuye ; Zhu, Peifen ; Zhu, Hongyang ; Qu, Yang ; Wang, Guofeng ( June 2022 , Journal of Materials Chemistry A)

   Improving the low charge separation efficiency, poor light absorption capacity, and insufficient active sites of photocatalysts are the important challenges for CO 2 photoreduction. In this study, a Mo modified InOOH/In(OH) 3 heterojunction with enhanced CO 2 reduction efficiency was synthesized in situ by using an In(OH) 3 monatomic lamellar material with isolated In atom sites exposed on its surface. And bandgap tuning via the energy levels formed by Mo doping and vacancy defect engineering can simultaneously improve visible light absorption and photogenerated charge separation. The results of experimental characterization and DFT calculation show that the Mo impurity energy levels, O defect energy levels, and surface Mo atoms existing in the InOOH phase can act as an electron transfer ladder in cooperation with the In defect energy levels in the In(OH) 3 phase, thereby promoting electron transfer between heterogeneous interfaces. Under visible light irradiation, the evolution rates of CH 4 and CO of the Mo modified InOOH/In(OH) 3 photocatalyst are more than ∼11 and ∼8 times higher than those of InOOH, respectively. This work provides new insights into the design of the CO 2 photoreduction platform through a collaborative strategy of bandgap tuning, transition metal doping, and heterostructure construction. 

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4. Structure and charge analysis of a cyclic aluminium hydride: cyclo -1,5-bis-μ-dimethylamino-3,7-di-μ-hydrido-2,4,6,8-tetrakis(dimethylaluminium)

   https://doi.org/10.1107/S2053229622011391  

   Corfield, Peter W. ; Schrier, Joshua ( January 2023 , Acta Crystallographica Section C Structural Chemistry)

   The title compound, [Al 4 (CH 3 ) 8 (C 2 H 7 N) 2 H 2 ], crystallizes as eight-membered rings with –(CH 3 ) 2 Al–(CH 3 ) 2 N–(CH 3 ) 2 Al– moieties connected by single hydride bridges. In the X-ray structure, the ring has a chair conformation, with the hydride H atoms being close to the plane through the four Al atoms. An optimized structure was also calculated by all-electron density functional theory (DFT) methods, which agrees with the X-ray structure but gives a somewhat different geometry for the hydride bridge. Charges on the individual atoms were determined by valence shell occupancy refinements using MoPro and also by DFT calculations analyzed by several different methods. All methods agree in assigning a positive charge to the Al atoms, negative charges to the C, N, and hydride H atoms, and small positive charges to the methyl H atoms. 

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5. Controlled One‐pot Synthesis of Nickel Single Atoms Embedded in Carbon Nanotube and Graphene Supports with High Loading

   https://doi.org/10.1002/cnma.202000223  

   Zhao, Shiyong ; Wang, Tianshuai ; Zhou, Guangmin ; Zhang, Liji ; Lin, Chao ; Veder, Jean‐Pierre ; Johannessen, Bernt ; Saunders, Martin ; Yin, Lichang ; Liu, Chang ; et al ( April 2020 , ChemNanoMat)

   Single‐atom catalysts (SACs) have attracted much attentions due to the advantages of high catalysis efficiency and selectivity. However, the controllable and efficient synthesis of SACs remains a significant challenge. Herein, we report a controlled one‐pot synthesis of nickel single atoms embedded on nitrogen‐doped carbon nanotubes (NiSA−N−CNT) and nitrogen‐doped graphene (NiSA−N−G). The formation of NiSA−N−CNT is due to the solid‐to‐solid rolling up mechanism during the high temperature pyrolysis at 800 °C from the stacked and layered Ni‐doped g‐C₃N₄, g‐C₃N₄−Ni structure to a tubular CNT structure. Addition of citric acid introduces an amorphous carbon source on the layered g‐C₃N₄−Ni and after annealing at the same temperature of 800 °C, instead of formation of NiSA−N−CNT, Ni single atoms embedded in planar graphene type supports, NiSA−N−G were obtained. The density functional theory (DFT) calculation indicates the introduction of amorphous carbon source substantially reduces the structure fluctuation or curvature of layered g‐C₃N₄‐Ni intermediate products, thus interrupting the solid‐to‐solid rolling process and leading to the formation of planar graphene type supports for Ni single atoms. The as‐synthesized NiSA−N−G with Ni atomic loading of ∼6 wt% catalysts shows a better activity and stability for the CO₂reduction reaction (CO₂RR) than NiSA−N−CNT with Ni atomic loading of ∼15 wt% due to the open and exposed Ni single atom active sites in NiSA−N−G. This study demonstrates for the first time the feasibility in the control of the microstructure of carbon supports in the synthesis of SACs.

    

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