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1. Influence of Rhenium Concentration on Charge Doping and Defect Formation in MoS ₂

   https://doi.org/10.1002/aelm.202400403  

   Munson, Kyle T; Torsi, Riccardo; Habis, Fatimah; Huberich, Lysander; Lin, Yu‐Chuan; Yuan, Yue; Wang, Ke; Schuler, Bruno; Wang, Yuanxi; Asbury, John B; et al (March 2025, Advanced Electronic Materials)

   Substitutionally doped transition metal dichalcogenides (TMDs) are essential for advancing TMD‐based field effect transistors, sensors, and quantum photonic devices. However, the impact of local dopant concentrations and dopant–dopant interactions on charge doping and defect formation within TMDs remains underexplored. Here, a breakthrough understanding of the influence of rhenium (Re) concentration is presented on charge doping and defect formation in MoS₂monolayers grown by metal–organic chemical vapor deposition (MOCVD). It is shown that Re‐MoS₂films exhibit reduced sulfur‐site defects, consistent with prior reports. However, as the Re concentration approaches ⪆2 atom%, significant clustering of Re in the MoS₂is observed. Ab Initio calculations indicate that the transition from isolated Re atoms to Re clusters increases the ionization energy of Re dopants, thereby reducing Re‐doping efficacy. Using photoluminescence (PL) spectroscopy, it is shown that Re dopant clustering creates defect states that trap photogenerated excitons within the MoS₂lattice, resulting in broad sub‐gap emission. These results provide critical insights into how the local concentration of metal dopants influences carrier density, defect formation, and exciton recombination in TMDs, offering a novel framework for designing future TMD‐based devices with improved electronic and photonic properties. 

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2. Extending Carrier Lifetimes in Lead Halide Perovskites with Alkali Metals by Passivating and Eliminating Halide Interstitial Defects

   https://doi.org/10.1002/anie.201911615  

   Qiao, Lu; Fang, Wei‐Hai; Long, Run; Prezhdo, Oleg V. (February 2020, Angewandte Chemie International Edition)

   Abstract Defects, such as halide interstitials, act as charge recombination centers, induce degradation of halide perovskites, and create major obstacles to applications of these materials. Alkali metal dopants greatly improve perovskite performance. Using ab initio nonadiabatic molecular dynamics, it is demonstrated that alkalis bring favorable effects. The formation energy of halide interstitials increases by up to a factor of four in the presence of alkali dopants, and therefore, defect concentration decreases. When defects are present, alkali metals strongly bind to them. Halide interstitials introduce mid‐gap states that rapidly trap charge carriers. Alkalis eliminate the trap states, helping to maintain high current density. Further to charge trapping, the interstitials accelerate charge recombination. By passivating the interstitials, alkalis make carrier lifetimes up to seven times longer than in defect‐free perovskites and up to thirty times longer than in defective perovskites. 

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3. Defective Ultrathin ZnIn ₂ S ₄ for Photoreductive Deuteration of Carbonyls Using D ₂ O as the Deuterium Source

   https://doi.org/10.1002/advs.202103408  

   Han, Chuang; Han, Guanqun; Yao, Shukai; Yuan, Lan; Liu, Xingwu; Cao, Zhi; Mannodi‐Kanakkithodi, Arun; Sun, Yujie (November 2021, Advanced Science)

   Abstract Deuterium (D) labeling is of great value in organic synthesis, pharmaceutical industry, and materials science. However, the state‐of‐the‐art deuteration methods generally require noble metal catalysts, expensive deuterium sources, or harsh reaction conditions. Herein, noble metal‐free and ultrathin ZnIn₂S₄(ZIS) is reported as an effective photocatalyst for visible light‐driven reductive deuteration of carbonyls to produce deuterated alcohols using heavy water (D₂O) as the sole deuterium source. Defective two‐dimensional ZIS nanosheets (D‐ZIS) are prepared in a surfactant assisted bottom‐up route exhibited much enhanced performance than the pristine ZIS counterpart. A systematic study is carried out to elucidate the contributing factors and it is found that the in situ surfactant modification enabled D‐ZIS to expose more defect sites for charge carrier separation and active D‐species generation, as well as high specific surface area, all of which are beneficial for the desirable deuteration reaction. This work highlights the great potential in developing low‐cost semiconductor‐based photocatalysts for organic deuteration in D₂O, circumventing expensive deuterium reagents and harsh conditions. 

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4. Enhanced Solar CO₂ Reduction Using Single Cobalt Sites on Carbon Nitride Modified with a Dianhydride

   https://doi.org/10.1021/acs.jpcc.4c08562  

   St_John, Allison; Xiang, Shuting; Flayhart, Hannah; Ortega, Eduardo; Qian, Qian; Deskins, N Aaron; Roldan_Cuenya, Beatriz; Rochford, Jonathan; Frenkel, Anatoly I; Li, Gonghu (April 2025, The Journal of Physical Chemistry C)

   Photoactive single-atom catalysts (SACs) are among the most exciting catalytic materials for solar fuel production. Different SACs, including our own Co SACs, have been prepared on graphitic carbon nitride (C3N4) for use in photocatalysis. Building on our prior success, we report here doped C3N4 using various supplemental carbon dopants as the support for Co SACs. The Co SAC on a dianhydride doped C3N4 showed the highest activity in photocatalytic CO2 reduction. Catalyst characterization was carried out to explore the origin of the enhanced activity of this particular Co SAC. The dianhydride doped C3N4 possesses unique microstructural features, including large inter-layer space and fibrous morphology, that could contribute to the enhanced photocatalytic activity. Our results further indicate that the dianhydride is the most effective dopant to incorporate aromatic moieties in C3N4, which resulted in improved charge separation and enhanced activity in photocatalysis. 

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5. Modeling the roles of rigidity and dopants in single-atom methane-to-methanol catalysts

   https://doi.org/10.1039/D1TA08502F  

   Jia, Haojun; Nandy, Aditya; Liu, Mingjie; Kulik, Heather J. (January 2022, Journal of Materials Chemistry A)

   Doped graphitic single-atom catalysts (SACs) with isolated iron sites have similarities to natural enzymes and molecular biomimetics that can convert methane to methanol via a radical rebound mechanism with high-valent Fe( iv )O intermediates. To understand the relationship of SACs to these homogeneous analogues, we use range-separated hybrid density functional theory (DFT) to compare the energetics and structure of the direct metal-coordinating environment in the presence of 2p ( i.e. , N or O) and 3p ( i.e. , P or S) dopants and with increasing finite graphene model flake size to mimic differences in local rigidity. While metal–ligand bond lengths in SACs are significantly shorter than those in transition-metal complexes, they remain longer than SAC mimic macrocyclic complexes. In SACs or the macrocyclic complexes, this compressed metal–ligand environment induces metal distortion out of the plane, especially when reactive species are bound to iron. As a result of this modified metal-coordination environment, we observe SACs to simultaneously favor the formation of the metal–oxo while also allowing for methanol release. This reactivity is different from what has been observed for large sets of square planar model homogeneous catalysts. Overall, our calculations recommend broader consideration of dopants ( e.g. , P or S) and processing conditions that allow for local distortion around the metal site in graphitic SACs. 

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