The role of formate species for CO₂ hydrogenation is still under debate. Although formate has been frequently observed and commonly proposed as the possible intermediate, there is no definite evidence for the reaction of formate species for methanol production. Here, formate formation and conversion over the ZnZrO_x solid solution catalyst are investigated by in situ/operando diffuse reflectance infrared Fourier transform spectroscopy-mass spectroscopy (DRIFTS-MS) coupled with density functional theory (DFT) calculations. Spectroscopic results show that bidentate carbonate formed from CO₂ adsorption is hydrogenated to formate on Zn-O-Zr sites (asymmetric sites), where the Zn site is responsible for H₂ activation and the Zr site is beneficial for the stabilization of reaction intermediates. The asymmetric Zn-O-Zr sites with adjacent and inequivalent features on the ZnZrO_x catalyst promote not only formate formation but also its transformation. Both theoretical and experimental results demonstrate that the origin of the excellent performance of the ZnZrO_x catalyst for methanol formation is associated with the H₂ heterolytic cleavage promoted by the asymmetric Zn and Zr sites.

Surface atomic arrangement and coordination of photocatalysts highly exposed to different crystal facets significantly affect the photoreactivity. However, controversies on the true photoreactivity of a specific facet in heterogeneous photocatalysis still exits. Herein, we exemplified well-defined BiOBr nanosheets dominating with respective facets, (001) and (010), to track the reactivity of crystal facets for photocatalytic water splitting. The real photoreactivity of BiOBr-(001) were evidenced to be significantly higher than BiOBr-(010) for both hydrogen production and oxygen evolution reactions. Further in situ photochemical probing studies verified the distinct reactivity is not only owing to the highly exposed facets, but dominated by the co-exposing facets, leading to an efficient spatial separation of photogenerated charges and further making the oxidation and reduction reactions separately occur with different reaction rates, which ordains the fate of the true photoreactivity.

Lead-free inorganic halide perovskites have triggered appealing interests in various energy-related applications including solar cells and photocatalysis. However, why perovskite-structured materials exhibit excellent photoelectric properties and how the unique crystalline structures affect the charge behaviors are still not well elucidated but essentially desired. Herein, taking inorganic halide perovskite Cs₃Bi₂Br₉ as a prototype, the significant derivation process of silver atoms incorporation to induce the structural transformation from Cs₃Bi₂Br₉ to Cs₂AgBiBr₆, which brings about dramatic differences in photoelectric properties is unraveled. It is demonstrated that the silver incorporation results in the co-operated orbitals hybridization, which makes the electronic distributions in conduction and valence bands of Cs₂AgBiBr₆ more dispersible, eliminating the strong localization of electron–hole pairs. As consequences of the electronic structures derivation, exhilarating changes in photoelectric properties like band structure, exciton binding energy, and charge carrier dynamics are verified experimentally and theoretically. Using photocatalytic hydrogen evolution activity under visible light as a typical evaluation, such crystalline structure transformation contributes to a more than 100-fold enhancement in photocatalytic performances compared with pristine Cs₃Bi₂Br₉, verifying the significant effect of structural derivations on the exhibited performances. The findings will provide evidences for understanding the origin of photoelectric properties for perovskites semiconductors in solar energy conversion.

Hydrogenation of CO₂ to methanol utilizing the hydrogen from renewable energy sources offers a promising way to reduce CO₂ emissions through the CO₂ utilization as a carbon source. However, it is a challenge to convert CO₂ to methanol with high activity and high methanol selectivity. Herein, we report a class of metal-oxide solid-solution catalysts: M_aZrO_x (M_a = Cd, Ga), which show a methanol selectivity up to 80% with the CO₂ single pass conversion reaching 4.3%-12.4% under the reaction conditions of H₂/CO₂ = 3/1, 24※000 h^-1, 5 MPa. Structural and electronic characterizations combined with denisty functional theory calculations suggest that the M_a and Zr components in M_aZrO_x (M_a = Cd, Ga) solid-solution catalysts show a strong synergetic effect, which enhances the H₂ heterolytic dissociation and results in high activity and high methanol selectivity. The solid-solution catalyst with dual metal oxide components offers an approach for the selective hydrogenation of CO₂ to chemicals.

This overview paper highlights the successes of the Ozone Monitoring Instrument (OMI) on board the Aura satellite spanning a period of nearly 14 years. Data from OMI has been used in a wide range of applications and research resulting in many new findings. Due to its unprecedented spatial resolution, in combination with daily global coverage, OMI plays a unique role in measuring trace gases important for the ozone layer, air quality, and climate change. With the operational very fast delivery (VFD; direct readout) and near real-time (NRT) availability of the data, OMI also plays an important role in the development of operational services in the atmospheric chemistry domain.

Although methanol synthesis via CO hydrogenation has been industrialized, CO₂ hydrogenation to methanol still confronts great obstacles of low methanol selectivity and poor stability, particularly for supported metal catalysts under industrial conditions. We report a binary metal oxide, ZnO-ZrO₂ solid solution catalyst, which can achieve methanol selectivity of up to 86 to 91% with CO₂ single-pass conversion of more than 10% under reaction conditions of 5.0 MPa, 24,000 ml/(g hour), H₂/CO₂ = 3:1 to 4:1, 320° to 315°C. Experimental and theoretical results indicate that the synergetic effect between Zn and Zr sites results in the excellent performance. The ZnO-ZrO₂ solid solution catalyst shows high stability for at least 500 hours on stream and is also resistant to sintering at higher temperatures. Moreover, no deactivation is observed in the presence of 50 ppm SO₂ or H₂S in the reaction stream.

The Ozone Monitoring Instrument (OMI) onboard NASA's Aura satellite has been providing global observations of the ozone layer and key atmospheric pollutant gases, such as nitrogen dioxide (NO2) and sulfur dioxide (SO2), since October 2004. The data products from the same instrument provide consistent spatial and temporal coverage and permit the study of anthropogenic and natural emissions on local-to-global scales. In this paper, we examine changes in SO2 and NO2 over some of the world's most polluted industrialized regions during the first decade of OMI observations. In terms of regional pollution changes, we see both upward and downward trends, sometimes in opposite directions for NO2 and SO2, for different study areas. The trends are, for the most part, associated with economic and/or technological changes in energy use, as well as regional regulatory policies. Over the eastern US, both NO2 and SO2 levels decreased dramatically from 2005 to 2015, by more than 40 and 80ĝ€%, respectively, as a result of both technological improvements and stricter regulations of emissions. OMI confirmed large reductions in SO2 over eastern Europe's largest coal-fired power plants after installation of flue gas desulfurization devices. The North China Plain has the world's most severe SO2 pollution, but a decreasing trend has been observed since 2011, with about a 50ĝ€% reduction in 2012–2015, due to an economic slowdown and government efforts to restrain emissions from the power and industrial sectors. In contrast, India's SO2 and NO2 levels from coal power plants and smelters are growing at a fast pace, increasing by more than 100 and 50ĝ€%, respectively, from 2005 to 2015. Several SO2 hot spots observed over the Persian Gulf are probably related to oil and gas operations and indicate a possible underestimation of emissions from these sources in bottom-up emission inventories. Overall, OMI observations have proved valuable in documenting rapid changes in air quality over different parts of the world during last decade. The baseline established during the first 11 years of OMI is indispensable for the interpretation of air quality measurements from current and future satellite atmospheric composition missions.