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Halide perovskites have distinguished themselves among the numerous optoelectronic materials due to their versatile processing technology and exceptional optical response. Unfortunately, their stability and toxicity from heavy metals severely hamper their development, in addition to the challenge of further improving photovoltaic performance. Hence, a lead-free perovskite-based heterojunction, C2N/CsGeI3, is investigated using a hybrid density functional, including electron structures, charge density differences, optical properties and more. The study reveals the presence of a built-in electric field directed from the CsGeI3 to the C2N layer. Moreover, based on the work function, it is confirmed that the electrons are transferred in a Z-scheme mechanism after the CsGeI3 contacts with the C2N layer. Under light irradiation, the construction of the C2N/CsGeI3 heterojunction significantly enhances optical absorption within the range of visible-light wavelengths. Additionally, the impact of interfacial strain on the C2N/CsGeI3 is explored and discussed. These findings not only suggest that the C2N/CsGeI3 heterojunction holds promise for photovoltaic applications but also provide a theoretical insight into lead-free perovskite-based functional materials. [ABSTRACT FROM AUTHOR]

Single–atom catalysts (SACs) have attracted wide attention to be acted as potential electrocatalysts for nitrogen reduction reaction (NRR). However, the coordination environment of the single transition metal (TM) atoms is essential to the catalytic activity for NRR. Herein, we proposed four types of 3‐, 4‐coordinated and π–d conjugated TMxB3N3S6 (x=2, 3, TM=Ti, V, Cr, Mn, Fe, Zr, Nb, Mo, Tc, Ru, Hf, Ta, W, Re and Os) monolayers for SACs. Based on density functional theory (DFT) calculations, I‐TM2B3N3S6 and III‐TM3B3N3S6 are the reasonable 3‐coordinated and 4‐coordinated structures screening by structure stable optimizations, respectively. Next, the structural configurations, electronic properties and catalytic performances of 30 kinds of the 3‐coordinated I‐TM2B3N3S6 and 4‐coordinated III‐TM3B3N3S6 monolayers with different single transition metal atoms were systematically investigated. The results reveal that B3N3S6 ligand is an ideal support for TM atoms due to existence of strong TM‐S bonds. The 3‐coordinated I‐V2B3N3S6 is the best SAC with the low limiting potential (UL) of −0.01 V, excellent stability (Ef=−0.32 eV, Udiss=0.02 V) and remarkable selectivity characteristics. This work not only provides novel π–d conjugated SACs, but also gives theoretical insights into their catalytic activities and offers reference for experimental synthesis. [ABSTRACT FROM AUTHOR]

Halide perovskites have distinguished themselves among the numerous optoelectronic materials due to their versatile processing technology and exceptional optical response. Unfortunately, their stability and toxicity from heavy metals severely hamper their development, in addition to the challenge of further improving photovoltaic performance. Hence, a lead-free perovskite-based heterojunction, C 2 N/CsGeI 3 , is investigated using a hybrid density functional, including electron structures, charge density differences, optical properties and more. The study reveals the presence of a built-in electric field directed from the CsGeI 3 to the C 2 N layer. Moreover, based on the work function, it is confirmed that the electrons are transferred in a Z-scheme mechanism after the CsGeI 3 contacts with the C 2 N layer. Under light irradiation, the construction of the C 2 N/CsGeI 3 heterojunction significantly enhances optical absorption within the range of visible-light wavelengths. Additionally, the impact of interfacial strain on the C 2 N/CsGeI 3 is explored and discussed. These findings not only suggest that the C 2 N/CsGeI 3 heterojunction holds promise for photovoltaic applications but also provide a theoretical insight into lead-free perovskite-based functional materials.

Single-atom catalysts (SACs) have attracted wide attention to be acted as potential electrocatalysts for nitrogen reduction reaction (NRR). However, the coordination environment of the single transition metal (TM) atoms is essential to the catalytic activity for NRR. Herein, we proposed four types of 3-, 4-coordinated and π-d conjugated TM x B 3 N 3 S 6 (x=2, 3, TM=Ti, V, Cr, Mn, Fe, Zr, Nb, Mo, Tc, Ru, Hf, Ta, W, Re and Os) monolayers for SACs. Based on density functional theory (DFT) calculations, I-TM 2 B 3 N 3 S 6 and III-TM 3 B 3 N 3 S 6 are the reasonable 3-coordinated and 4-coordinated structures screening by structure stable optimizations, respectively. Next, the structural configurations, electronic properties and catalytic performances of 30 kinds of the 3-coordinated I-TM 2 B 3 N 3 S 6 and 4-coordinated III-TM 3 B 3 N 3 S 6 monolayers with different single transition metal atoms were systematically investigated. The results reveal that B 3 N 3 S 6 ligand is an ideal support for TM atoms due to existence of strong TM-S bonds. The 3-coordinated I-V 2 B 3 N 3 S 6 is the best SAC with the low limiting potential (U L ) of -0.01 V, excellent stability (E f =-0.32 eV, U diss =0.02 V) and remarkable selectivity characteristics. This work not only provides novel π-d conjugated SACs, but also gives theoretical insights into their catalytic activities and offers reference for experimental synthesis., (© 2023 Wiley-VCH GmbH.)