Hybrid two-dimensional (2D) lead halide perovskites have been employed in optoelectronic applications, including white light emission for light emitting diodes (LEDs). However, until now, there have been limited reports on white light emitting lead halide perovskites with experimental insights into the mechanism of the broad band emission. Here, we present white light emission from a 2D hybrid lead chloride perovskite, using the widely known phenethylammonium cation. The single crystal X-ray structural data, time-resolved photophysical measurements, and DFT calculations are consistent with broad band emission arising from strong exciton-phonon coupling with the organic lattice, which is independent of surface defects. The phenethylammonium lead chloride material exhibits a remarkably high color rendering index of 84, CIE coordinate of (0.37,0.42), CCT of 4426, and photostability, making it ideal for natural white LEDs applications.

Chemoselective aliphatic carbon–carbon bond activation photocatalyzed by vanadium oxo complexes under ambient conditions and visible light.

Mechanochemistry is a green, solid-state, re-emerging synthetic technique that can rapidly form complex molecules and materials without exogenous heat or solvent(s). Herein, we report the application of solvent-free mechanochemical ball milling for the synthesis of metal halide perovskites, to overcome problems with solution-based syntheses. We prepared phase-pure, air-sensitive CsSnX 3 (X = I, Br, Cl) and its mixed halide perovskites by mechanochemistry for the first time by reactions between cesium and tin(II) halides. Notably, we report the sole examples where metastable, high-temperature phases like cubic CsSnCl 3 , cubic CsPbI 3 , and trigonal FAPbI 3 were accessible at ambient temperatures and pressures without post-synthetic processing. The perovskites can be prepared up to ''kilogram scales.'' Lead-free, all-inorganic photodetector devices were fabricated using the mechanosynthesized CsSnBr 1.5 Cl 1.5 under solvent-free conditions and showed 10-fold differences between on-off currents. We highlight an essentially solvent-free, general approach to synthesize metastable compounds and fabricate photodetectors from commercially available precursors.

In an artificial photosynthetic system, separation of the catalytic sites for water oxidation from those of carbon dioxide reduction by a gas impermeable physical barrier is an important requirement for avoiding cross and back reactions. Here, an approach is explored that uses crystalline Co3O4 as an oxygen evolving catalyst and a nanometer-thin dense phase silica layer as the separation barrier. For controlled charge transport across the barrier, hole conducting molecular wires are embedded in the silica. Spherical Co3O4(4 nm)–SiO2(2 nm) core–shell nanoparticles with p-oligo(phenylenevinylene) wire molecules (three aryl units, PV3) cast into the silica were developed to establish proof of concept for charge transport across the embedded wire molecules. FT-Raman, FT-infrared, and UV–visible spectroscopy confirmed the integrity of the organic wires upon casting in silica. Transient optical absorption spectroscopy of a visible light sensitizer (ester derivatized [Ru(bpy)3]2+ complex) indicates efficient charge injection into Co3O4–SiO2 particles with embedded wire molecules in aqueous solution. An upper limit of a few microseconds is inferred for the residence time of the hole on the embedded PV3 molecule before transfer to Co3O4 takes place. The result was corroborated by light on/off experiments using rapid-scan FT-IR monitoring. These observations indicate that hole conducting organic wire molecules cast into a dense phase, nanometer thin silica layer offer fast, controlled charge transfer through a product-separating oxide barrier.

Two‐dimensional lead and tin halide perovskites were prepared by intercalating the long alkyl group 1‐hexadecylammonium (HDA) between the inorganic layers. We observed visible‐light absorption, narrow‐band photoluminescence, and nanosecond photoexcited lifetimes in these perovskites. Owing to their hydrophobicity and stability even in humid air, we applied these perovskites in the decarboxylation and dehydrogenation of indoline‐2‐carboxylic acids. (HDA)2PbI4 or (HDA)2SnI4 were investigated as photoredox catalysts for these reactions, and quantitative conversion and high yields were observed with the former.

Significant efforts are devoted to developing artificial photosynthetic systems to produce fuels and chemicals in order to cope with the exacerbating energy and environmental crises in the world now. Nonetheless, the large-scale reactions that are the focus of the artificial photosynthesis community, such as water splitting, are thus far not economically viable, owing to the existing, cheaper alternatives to the gaseous hydrogen and oxygen products. As a potential substitute for water oxidation, here, a unique, visible light-driven oxygenation of carboncarbon bonds for the selective transformation of 32 unactivated alcohols, mediated by a vanadium photocatalyst under ambient, atmospheric conditions is presented. Furthermore, since the initial alcohol products remain as substrates, an unprecedented photodriven cascade carboncarbon bond cleavage of macromolecules can be performed. Accordingly, hydroxyl-terminated polymers such as polyethylene glycol, its block co-polymer with polycaprolactone, and even the non-biodegradable polyethylene can be repurposed into fuels and chemical feedstocks, such as formic acid and methyl formate. Thus, a distinctive approach is presented to integrate the benefits of photoredox catalysis into environmental remediation and artificial photosynthesis.

Plastic waste remains a global challenge due to the massive amounts being produced without satisfactory treatment technologies for recycling and upcycling. Photocatalytic processes are emerging as green and promising approaches to upcycle plastics into value‐added products under mild conditions using sunlight as the energy source. In this review, the recent advances in plastic conversion through photocatalysis have been comprehensively summarized. Special emphasis is placed on the photocatalytic mechanism and the selective CC and CH bond transformations of plastics to access fuels, chemicals, and materials. Finally, the challenges and the perspectives on establishing a new paradigm toward a sustainable and circular plastic economy are also put forward.

Oxo-bridged heterobinuclear units of the type Zr(IV)OCo(II) covalently anchored on the pore surface of mesoporous silica SBA-15 have been synthesized with high selectivity. The unit exhibits a visible light absorbing metal-to-metal charge-transfer absorption (MMCT) extending to about 550 nm. The oxo-bridged structure of the binuclear moiety is manifested by spectral blue-shifts of the optical Co(II) spin−orbit bands due to reduced π-electron donating ability of the bridging oxygen caused by the electron-withdrawing Zr center. EXAFS measurements of the Zr and Co K-edges and curve fitting analysis revealed a Zr to Co distance of 3.4 Å. The coordination geometry of the Zr and Co metal centers in monometallic Zr and Co-SBA-15 samples is closely preserved in the ZrOCo unit. Illumination of the MMCT absorption at 420 nm and shorter wavelengths resulted in the reduction of CO 2 to gas phase CO and HCO 2 − , the latter adsorbed on the silica pore surface. The branching between carbon monoxide and formate was found to be determined by the fate of the sacrificial donor (triethyl-or diethylamine), namely proton transfer versus H atom transfer to CO 2 interacting with the transient Zr(III) center. The ZrOCo(II) unit on a silica surface constitutes the first example of an all-inorganic heterobinuclear unit for the photoinduced splitting of CO 2 to free CO. Moreover, transient Co(III) formed upon MMCT excitation should possess sufficient oxidation potential for driving a catalyst for water oxidation, thereby opening up opportunities for replacing the sacrificial donor by water as electron source.