Inorganic perovskite quantum dots as optoelectronic materials have attracted enormous attention in light-harvesting and emitting devices. However, photocatalytic conversion based on inorganic perovskite halides has not been reported. Here, we have synthesized colloidal quantum dots (QDs, 3-12 nm) of cesium lead halide perovskites (CsPbBr ) as a new type of photocatalytic material. The band gap energies and photoluminescence (PL) spectra are tunable over the visible spectral region according to quantum size effects on an atomic scale. The increased carrier lifetime revealed by time-resolved PL spectra, indicates the efficient electron-hole separation and transfer. As expected, the CsPbBr QDs with high selectivity of greater than 99 % achieve an efficient yield of 20.9 μmol g towards solar CO reduction. This work has opened a new avenue for inorganic colloidal perovskite materials as efficient photocatalysts to convert CO into valuable fuels.

Photocatalytic hydrogen evolution from pure water is successfully realized by using interstitial P-doped CdS with rich S vacancies (CdS-P) as the photocatalyst in the absence of any electron sacrificial agents. Through interstitial P doping, the impurity level of S vacancies is located near the Fermi level and becomes an effective electron trap level in CdS-P, which can change dynamic properties of photogenerated electrons and thus prolong their lifetimes. The long-lived photogenerated electrons are able to reach the surface active sites to initiate an efficient photocatalytic redox reaction. Moreover, the photocatalytic activity of CdS-P can be further improved through the loading of CoP as a cocatalyst.

Mid-infrared (IR) nonlinear optical (NLO) materials with high performance are vital to expanding the laser wavelengths into the mid-IR region and have important technological applications in many civil and military fields. For the last two decades metal chalcogenides have attracted great attention since many of them possess a large NLO effect, wide transparent range, moderate birefringence, and high resistance to laser damage. However, the discovery of superior mid-IR NLO metal chalcogenides is still a big challenge mainly due to the difficulty of achieving a good balance between the NLO effect and laser damage threshold (LDT). In this review, metal chalcogenides are catalogued according to the different types of microscopic building blocks. These groups include triangle planar units, tetrahedral metal-centered units, polyhedra with second-order John-Teller cations, and polyhedra with stereochemically active lone electron pairs cations, rare-earth cations, and/ or halogen anions. The determinations of these microscopic structures on mid-IR NLO properties in metal chalcogenides are summarized and analyzed combined with available experimental data and first-principle calculations. From the deduced structure−property relationship, the searching directions for new metal chalcogenides that have good mid-IR NLO performances, especially for achieving the balance between large NLO effect and high LDT, are discussed.