N‐doped TiO₂‐quantum dots tightly anchored on graphene with superior interfacial contact via C–Ti bond

Abstract

A novel composite of N-doped TiO 2 -quantum dots tightly anchored on graphene (denoted as N-doped TiO 2 -QDs@GP) with superior interfacial contact via C-Ti bond was synthesized via the simple one-pot vapor-thermal method. The as-obtained N-doped TiO 2 -QDs@GP includes TiO 2 QDs with an average size of 3.28 nm uniformly distributed on the surface of GP. The large specific area and superior interfacial contact via C-Ti bond ensured its potential photocatalytic application. Except for the effective interfacial charge transfer achieved via C-Ti chemical bond between TiO 2 QDs and GP, its enhanced visible light absorption and larger oxygen vacancy ratio also make contributions. Electron spin resonance spectra (ESR) were used to study the photocatalytic mechanism, which proved the participation of both superoxide radical (ÁO 2 À ) and hydroxyl radical (ÁOH) in the photocatalytic reactions. This work provides a promising one-pot method for constructing intimately contacted N-doped TiO 2 /GP composite with superior interfacial contact via C-Ti bond and excellent photocatalytic activities.

CuI/BaSnO3 Quantum Dot/ZnSnO3 Perovskite-based Transparent p–n Junction for Photovoltaic Enhancement

“…The X-ray photoelectron spectroscopy (XPS) showed peaks at 1021.12 and 1044.18 eV corresponding to Zn 2+ (Figure S1a), peaks at 779.77 and 795.02 eV corresponding to Ba 2+ (Figure S1b), peaks at 486.01 and 494.43 eV corresponding to Sn 2+ (Figure S1c), and peaks at 529.78 and 531.45 eV corresponding to Sn–O bonds and −OH groups of absorbed water (Figure S1d). These peaks confirm the formation of perovskite ZnSnO 3 film and the deposition of the perovskite BaSnO 3 QD. ,,− Further, peaks at 932.02 and 951.74 eV corresponded to Cu + (Figure S1e), indicating the presence of cuprous Cu, which exhibits good stability. − Peaks at 619.23 and 630.70 eV were observed for I – (Figure S1f), indicating the thorough removal of iodine powder and the formation of the CuI film. , Thus, the CuI/BaSnO 3 QD/ZnSnO 3 perovskite-based transparent p–n junction with homologous perovskite BaSnO 3 QD is successfully formed.…”

“…28−30 Peaks at 619.23 and 630.70 eV were observed for I − (Figure S1f), indicating the thorough removal of iodine powder and the formation of the CuI film. 53,54 Thus, the CuI/BaSnO 3 QD/ZnSnO 3 perovskite-based transparent p−n junction with homologous perovskite BaSnO 3 QD is successfully formed.…”

“…CuI/ZSO-BSO-2 exhibited a photovoltaic enhancement of ∼2.6 × 10 3 folds, with a slight decrease in transparency of ∼5–7%. This indicates that the regulation of carrier behavior by the homologous perovskite BaSnO 3 QD’s transition layer is more important than simple absorption. − The homologous perovskite BaSnO 3 QD at the interface of CuI/ZnSnO 3 act as a ladder to promote the transfer of photo-generated carriers while maintaining decent transparency and increasing carrier injection through their high QY. , Additionally, Cu vacancies induce hole-related carriers, optimizing the intrinsic defects. − The synergistic effects of appropriate Fermi level, high QY of homologous perovskite BaSnO 3 QD, and p-type carrier induced by Cu vacancies enable the achievement of a favorable kinetic equilibrium for high PCE. ,− , Therefore, by modifying with the dual-functional homologous perovskite BaSnO 3 QD, the CuI/BaSnO 3 QD/ZnSnO 3 obtains a decent balance between PCE and transparency. − , Additionally, the excellent physical–chemical stability of inorganic perovskite BaSnO 3 QD and ZnSnO 3 contributes to the overall stability. − ,− …”

“…53 Additionally, the small size of perovskite QD optimizes interface contact and further improves the formed p−n junction. 54,55 Herein, CuI/BaSnO 3 QD/ZnSnO 3 perovskite-based transparent p−n junction was prepared with homologous perovskite BaSnO 3 QD's transition layer using a hybrid approach involving sol−gel, freeze-drying, annealing, and sputtering. The CuI/BaSnO 3 QD/ZnSnO 3 perovskite-based transparent p−n junction exhibits a high transmittance of ∼85% and a photovoltaic enhancement of ∼2.6 × 10 3 folds compared to CuI/ZnSnO 3 (PCE of ∼1.13%).…”

“…In the case of homologous BaSnO 3 QD, , which possess high QY, high carrier mobility, and an appropriate potential structure, their similar perovskite crystal structure to ZnSnO 3 provides a more relaxed potential transitions and high-quality interface lattice matching, thereby improving carrier efficiency. − For example, Sun et al used BaSnO 3 nanoparticles as an electronic transport layer to reduce leakage current, enhance interface extraction, and decrease charge transfer resistance in perovskite solar cells . Additionally, the small size of perovskite QD optimizes interface contact and further improves the formed p–n junction. , …”