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Solar‐energy‐driven photoreduction of CO2 is promising in alleviating environment burden, but suffers from low efficiency and over‐reliance on sacrificial agents. Herein, rhenium (Re) is atomically dispersed in In2O3 to fabricate a 2Re‐In2O3 photocatalyst. In sacrificial‐agent‐free photoreduction of CO2 with H2O, 2Re‐In2O3 shows a long‐term stable efficiency which is enhanced by 3.5 times than that of pure In2O3 and is also higher than those on Au‐In2O3, Ag‐In2O3, Cu‐In2O3, Ir‐In2O3, Ru‐In2O3, Rh‐In2O3 and Pt‐In2O3 photocatalysts. Moreover, carbon‐based product of the photoreduction overturns from CO on pure In2O3 to CH3OH on 2Re‐In2O3. Re promotes charge separation, H2O dissociation and CO2 activation, thus enhancing photoreduction efficiency of CO2 on 2Re‐In2O3. During the photoreduction, CO is a key intermediate. CO prefers to desorption rather than hydrogenation on pure In2O3, as CO binds to pure In2O3 very weakly. Re strengthens the interaction of CO with 2Re‐In2O3 by 5.0 times, thus limiting CO desorption but enhancing CO hydrogenation to CH3OH. This could be the origin for photoreduction product overturn from CO on pure In2O3 to CH3OH on 2Re‐In2O3. The present work opens a new way to boost sacrificial‐agent‐free photoreduction of CO2. [ABSTRACT FROM AUTHOR]

The pressure dependent reaction mechanism of CO2 hydrogenation over In2O3 was investigated. CO2 hydrogenation on In2O3 can produce methanol only at high pressure, while the atmospheric pressure operation leads to the formation of CO. The conversion from HCOO* to H3CO* is accelerated at high pressure, leading to the formation of methanol with the formate route (CO2* → HCOO* → H3CO* → H3COH). [ABSTRACT FROM AUTHOR]

Summary: Grass lignocelluloses feature complex compositions and structures. In addition to the presence of conventional lignin units from monolignols, acylated monolignols and flavonoid tricin also incorporate into lignin polymer; moreover, hydroxycinnamates, particularly ferulate, cross‐link arabinoxylan chains with each other and/or with lignin polymers. These structural complexities make grass lignocellulosics difficult to optimize for effective agro‐industrial applications. In the present study, we assess the applications of two engineered monolignol 4‐O‐methyltransferases (MOMTs) in modifying rice lignocellulosic properties. Two MOMTs confer regiospecific para‐methylation of monolignols but with different catalytic preferences. The expression of MOMTs in rice resulted in differential but drastic suppression of lignin deposition, showing more than 50% decrease in guaiacyl lignin and up to an 90% reduction in syringyl lignin in transgenic lines. Moreover, the levels of arabinoxylan‐bound ferulate were reduced by up to 50%, and the levels of tricin in lignin fraction were also substantially reduced. Concomitantly, up to 11 μmol/g of the methanol‐extractable 4‐O‐methylated ferulic acid and 5–7 μmol/g 4‐O‐methylated sinapic acid were accumulated in MOMT transgenic lines. Both MOMTs in vitro displayed discernible substrate promiscuity towards a range of phenolics in addition to the dominant substrate monolignols, which partially explains their broad effects on grass phenolic biosynthesis. The cell wall structural and compositional changes resulted in up to 30% increase in saccharification yield of the de‐starched rice straw biomass after diluted acid‐pretreatment. These results demonstrate an effective strategy to tailor complex grass cell walls to generate improved cellulosic feedstocks for the fermentable sugar‐based production of biofuel and bio‐chemicals. [ABSTRACT FROM AUTHOR]

There exist always some H2S in natural gas. The industrialized process for H2S removal is an energy intense process and must be applied in a large scale. An alternative process is needed. Herein, we report a removal of H2S from a model natural gas mixture with methane, ethane and propane by dielectric barrier discharge (DBD), with which the dielectric (quartz) is frosted and coated with a layer of zeolite imidazole framework-67 (ZIF-67) nanoparticles. Compared to the DBD without coating, the average electric field as well as the mean electron energy of the DBD with ZIF-67 coating are higher at the same specific energy input (SEI), leading to a high H2S conversion of 75.4% with the limited conversion of methane (less than 2%). No conversions of other low alkanes can be detected. This provides a potential way for the H2S removal from the natural gas sources in the remote or isolated region. [ABSTRACT FROM AUTHOR]