Converting CO2 into chemical fuels with a photocatalyst and sunlight is an appealing approach to address climate deterioration and energy crisis. Metal complexes are superb candidates for CO2 reduction due to their tunable catalytic sites with high activity. The coupling of metal complexes with organic photosensitizers is regarded as a common strategy for establishing photocatalytic systems for visible-light-driven CO2 reduction. While most of the organic photosensitizers generally contain precious metals and are available through onerous synthetic routes, their large-scale application in the photocatalysis is limited. Halide perovskite nanocrystals (NCs) have been considered as one of the most promising light-harvesting materials to replace the organic photosensitizers due to their tunable light absorption range, low cost, abundant surface sites, and high molar extinction coefficient. Herein, we demonstrate a facile strategy to immobilize [Ni­(terpy)2]2+ (Ni­(tpy)) on inorganic ligand-capped CsPbBr3 NCs and to apply this hybrid as a catalyst for visible-light-driven CO2 reduction. In this hybrid photocatalytic system, the Ni­(tpy) can provide specific catalytic sites and serve as electron sinks to suppress electron–hole recombination in the CsPbBr3 NCs. The CsPbBr3-Ni­(tpy) catalytic system achieves a high yield (1724 μmol/g) in the reduction of CO2 to CO/CH4, which is approximately 26-fold higher than that achieved with the pristine CsPbBr3 NCs. This work has developed a method for enhancing the performance of photocatalytic CO2 reduction by immobilizing metal complexes on perovskite NCs. The methodology we present here provides a new platform for utilizing halide perovskite NCs for photocatalytic applications.

All inorganic lead halide perovskite nanocrystals (PNCs) typically suffer from poor stability against moisture and UV radiation as well as degradation during thermal treatment. The stability of PNCs can be significantly enhanced through polymer encapsulation, often accompanied by a decrease of photoluminescence quantum yield (PLQY) due to the loss of highly dynamic oleylamine/oleic acid (OLA/OA) ligands. Herein, we propose a solution for this problem by utilizing partially hydrolyzed poly(methyl methacrylate) (h-PMMA) and highly branched poly(ethylenimine) (b-PEI) as double ligands stabilizing the PNCs already during the mechanochemical synthesis (grinding). The hydrophobic polymer of h-PMMA imparts excellent film-forming properties and water stability to the resulting NC−polymer composite. In its own turn, the b-PEI forms an amino-rich, strongly binding ligand layer on the surface of the PNCs being responsible for the significant improvement of the PLQY and the stability of the resulting material. Moreover, the introduction of b-PEI promotes a partial phase conversion from CsPbBr 3 to CsPb 2 Br 5 to obtain CsPbBr 3 /CsPb 2 Br 5 nanocrystals with a core− shell-like structure. As-prepared PNCs solutions are directly processable as inks, while their PLQY drops only slightly from 75% in colloidal solution to 65% in films. Moreover, the final PNC−polymer film exhibits excellent stability against water, heat, and ultraviolet light irradiation. These superior properties allowed us to fabricate a proof of concept thin film OLED with h-PMMA/b-PEI-stabilized PNCs as an easily processable, narrowly emitting color conversion composite material. KEYWORDS: CsPbBr 3 −CsPb 2 Br 5 , partially hydrolyzed PMMA, highly branched PEI, high photoluminescence quantum yield, stability B ecause of their excellent photophysical properties, such as adjustable band gaps, high molar extinction coefficients, and excellent charge−transfer performance, all-inorganic cesium lead halide perovskite nanomaterials CsPbX 3 (X = Cl, Br, or I) have been perfect candidates for many optoelectronic applications, such as solar cells, 1 LEDs, 2,3 lasers, 4 photodetectors, 5 field effect transistors (FETs), 6 and Xray scintillators. 7 However, moisture, heat, and oxygen make perovskite nanomaterials suffering from poor stability. 8,9 For example, they dissolve in polar solvents, such as water, due to the ionic nature of the material itself. Additionally, perovskite nanomaterials easily undergo phase transitions and decompose

Noble metal aerogels (NMAs) are an emerging class of porous materials. Embracing nano‐sized highly‐active noble metals and porous structures, they display unprecedented performance in diverse electrocatalytic processes. However, various impurities, particularly organic ligands, are often involved in the synthesis and remain in the corresponding products, hindering the investigation of the intrinsic electrocatalytic properties of NMAs. Here, starting from laser‐generated inorganic‐salt‐stabilized metal nanoparticles, various impurity‐free NMAs (Au, Pd, and Au‐Pd aerogels) were fabricated. In this light, we demonstrate not only the intrinsic electrocatalytic properties of NMAs, but also the prominent roles played by ligands in tuning electrocatalysis through modulating the electron density of catalysts. These findings may offer a new dimension to engineer and optimize the electrocatalytic performance for various NMAs and beyond.

Unambiguously direct adsorption (DA) of initial oil-soluble quantum dots (QDs) on TiO film electrode is a convenient and simple approach in the construction of quantum dot sensitized solar cells (QDSCs). Regrettably, low QD loading amount and poor reproducibility shadow the advantages of DA route and constrain its practical application. Herein, the influence of experimental variables in DA process on QD loading amount as well as on the photovoltaic performance of the resultant QDSCs was investigated and optimized systematically, including the choice of solvent, purification of QDs, and sensitization time, as well as QD concentration. Experimental results demonstrated that it is essential to choose appropriate solvent as well as control purification cycles of original QD suspensions so as to realize satisfactory QD loading amount and ensure the high reproducibility. In addition, DA mode renders efficient electron injection from QD to TiO, yet low QD loading amount and adverse QD agglomeration in comparison with the well-developed capping ligand induced self-assembly (CLIS) deposition approach. Mg treatment on TiO photoanodes can promote the QD loading amount in DA mode. The optimized QDSCs based on DA mode exhibited efficiencies of 6.90% and 9.02% for CdSe and Zn-Cu-In-Se QDSCs, respectively, which were comparable to the best results based on CLIS mode (6.88% and 9.56%, respectively).

Noble-metal aerogels are emerging functional porous materials that have been applied in diverse fields. Among them, gold (Au) aerogels have displayed grand potentials in a wide range of catalytic processes. However, current fabrication methods fall short in obtaining Au gels with small ligament sizes and controlled surface valence states, which hinder the study of the underlying catalytic mechanisms. Here, a new approach of producing Au aerogels is reported. Via a two-phase ligand exchange, the long-chain ligands (oleylamine) of the as-prepared Au nanoparticles were replaced by short sulfide ions and subsequently self-assembled into three-dimensional gels. As a result, Au aerogels with small ligament sizes (ca. 3–4 nm) and tunable surface valence states are acquired. Taking the application for peroxidase mimics as an example, by correlating the surface valence with the catalytic properties, Au­(I) is found to be the active site for H2O2 and substrate-binding site for 3,3′,5,5′-tetramethylbenzidine, paving a new avenue for on-target devising Au-based catalysts.