ZnxIn2S3+x has emerged as a promising candidate for alcohol photoreforming based on C-H activation and C-C coupling. However, the underlying structure-activity-selectivity relationships remain unclear. Here we report on ZnxIn2S3+x with varying Zn:In:S ratios for visible-light-driven furfuryl alcohol reforming into H2 and hydrofuroin, a jet fuel precursor, via C-H activation and C-C coupling. S-• radicals are directly identified as the catalytically active sites responsible for C-H activation in furfuryl alcohol, promoting selectivity toward H2 and hydrofuroin. The optimum ZnxIn2S3+x activity derives from a trade-off between enhanced carrier dynamics and diminished visible light absorption as the x value in ZnxIn2S3+x increases. Further, a higher Zn-S:In-S layer ratio prolongs the S-• lifetime in the Zn-S layer, promoting C-H activation and delivering a higher C-C coupling product selectivity. The findings represent a step toward further establishing sulfide-based photocatalysts for sustainable H2 production via organic photoreforming.
Photoreforming enables simultaneous H2 production and organic synthesis in a one-pot system. In this study, a single-step synthesis approach was employed to fabricate atomically dispersed Ni in Zn3In2S6 (NixZIS) for benzyl alcohol photoreforming. While neat ZIS exhibits high selectivity toward hydrobenzoin via C-H activation and C-C coupling, its H2 evolution rate remains below feasible levels. Incorporating Ni single atoms significantly enhances ZIS activity by improving the carrier dynamics, resulting in an optimal H2 evolution rate of 9.13 mmol g-1 h−1 on Ni4ZIS, over five times higher than neat ZIS. The presence of Ni single atoms also alters selectivity, suppressing C-C coupling products and promoting benzaldehyde generation. The Ni single atoms induce facile O-H activation following the C-H activation of benzyl alcohol on ZIS, inhibiting the desorption of carbon radicals and causing consecutive oxidation to benzaldehyde. This study elucidates the role of Ni single atoms in driving activity and selectivity during organic photoreforming.
Perovskite photovoltaics have emerged as highly promising candidates for next-generation solar cells, achieving impressive power conversion efficiencies surpassing 22%, rivaling traditional silicon solar cells. Their advantages include lower manufacturing costs, tunable bandgaps, and potential for flexible, lightweight designs. However, the widespread use of lead (Pb) in perovskite absorbers raises significant environmental and health concerns. As a solution, researchers are exploring tin (Sn) as a non-toxic alternative due to its comparable electronic configuration, which may enable it to substitute lead without substantially compromising efficiency. In this study, SCAPS-1D software was employed to simulate lead-free tin-based perovskite solar cells, with a focus on analyzing how varying interface defect densities affect cell performance. Key cell parameters examined included the doping concentration of the perovskite absorption layer and the defect density within the perovskite bulk. Defect density is critical as it creates recombination centers that impede charge transport and decrease device efficiency. Findings from this simulation show that reducing defect density in the perovskite absorption layer notably improves overall cell performance, enhancing charge carrier mobility and reducing recombination losses. To further investigate interface effects, two specific interfaces were introduced: the TiO₂/perovskite interface, which serves as an electron transport layer, and the perovskite/hole transport material (HTM) interface. Analysis revealed that the TiO₂/perovskite interface plays a more substantial role in device performance, primarily due to its influence on carrier density and recombination rates, which are higher at this interface and critical in determining cell efficiency. Optimization of these parameters enabled the simulation of a device reaching a maximum efficiency of 24.63%. This research highlights the importance of interface engineering and defect management in tin-based, lead-free perovskite solar cells, demonstrating a feasible pathway toward environmentally sustainable, high-efficiency photovoltaics.
Abstract Perovskite photovoltaics are gaining prominence as highly efficient solar cell alternatives, surpassing 22% efficiency. However, the use of environmentally harmful lead poses a challenge. Tin (Sn) has emerged as a promising replacement for lead. This study employed SCAPS-1D software to simulate lead-free perovskite solar cells and investigate the impact of interface defect density. Various cell parameters, such as the doping concentration of the perovskite absorption layer and defect density of the perovskite absorber layer, were examined. Lowering the defect density in the perovskite absorption layer significantly improved overall cell performance. Two interface layers, TiO2/perovskite and perovskite/hole transport material (HTM), were introduced to assess their effect on cell performance. The TiO2/perovskite interface had a greater impact due to higher carrier density and increased recombination rates. Through parameter optimization, a maximum efficiency of 24.63% was achieved.
CuS is a unique semiconductor with potential in optoelectronics. Its unusual electronic structure, including a partially occupied valence band, and complex crystal structure with an S-S bond offer unique opportunities and potential applications. In this work, the use of doping to optimize the properties of CuS for various applications is investigated by density functional theory (DFT) calculations. Among the dopants studied, Ni, Zn, and Mg may be the most practical due to their lower formation energies. Doping with Fe, Ni, or Ca induces significant distortion, which may be beneficial for achieving materials with high surface areas and active states. Significantly, doping alters the conductor-like behavior of CuS, opening a band gap by increasing bond ionicity and reducing the S-S bond covalency. Thus, doping CuS can tune the plasmonic properties and transform it from a conductor to an intrinsic fluorescent semiconductor. Ni and Fe doping give the lowest band gaps (0.35 eV and 0.39 eV, respectively), while Mg doping gives the highest (0.86 eV). Doping with Mg, Ca, and Zn may enhance electron mobility and charge separation. Most dopants increase the anisotropy of electron-to-hole mass ratios, enabling device design that exploits directional-dependence for improved performance.
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