Advanced semiconductor catalyst designs for the photocatalytic reduction of CO_(2)

Using clean solar energy to reduce CO_(2)into value-added products not only consumes the over-emitted CO_(2)that causes environmental problems,but also generates fuel chemicals to alleviate energy crises.The photocatalytic CO_(2)reduction reaction(PCO_(2)RR)relies on the semiconductor photocatalysts that suffer from high recombination rate of the photo-generated carriers,low light harvesting capability,and low stability.This review explores the recent discoveries on the novel semiconductors for PCO_(2)RR,focusing on the rational catalyst design strategies(such as surface engineering,band engineering,hierarchical structure construction,single-atom catalysts,and biohybrid catalysts)that promote the catalytic performance of semiconductor catalysts on PCO_(2)RR.The advanced characterization techniques that contribute to understanding the intrinsic properties of the photocatalysts are also discussed.Lastly,the perspectives on future challenges and possible solutions for PCO_(2)RR are presented.

Soil microbial communities regulate the threshold effect of salinity stress on SOM decomposition in coastal salt marshes

Salinity stress is one of the critical environmental drivers of soil organic matter(SOM)decomposition in coastal ecosystems.Although the temperature sensitivity(Q_(10))of SOM decomposition has been widely applied in Earth system models to forecast carbon processes,the impact of salinity on SOM decomposition by restructuring microbial communities remains uncovered.Here,we conducted a microcosm experiment with soils collected from the coastal salt marsh in the Yellow River Estuary,which is subjected to strong dynamics of salinity due to both tidal flooding and drainage.By setting a gradient of salt solutions,soil salinity was adjusted to simulate salinity stress and soil carbon emission(CO_(2))rate was measured over the period.Results showed that as salinity increased,the estimated decomposition constants based on first-order kinetics gradually decreased at different temperatures.Below the 20‰salinity treatments,which doubled the soil salinity,Q_(10)increased with increasing salinity;but higher salinity constrained the temperature-related response of SOM decomposition by inhibiting microbial growth and carbon metabolisms.Soil bacteria were more sensitive to salinity stress than fungi,which can be inferred from the response of microbial beta-diversity to changing salinity.Among them,the phylotypes assigned to Gammaproteobacteria and Bacilli showed higher salt tolerance,whereas taxa affiliated with Alphaproteobacteria and Bacteroidota were more easily inhibited by the salinity stress.Several fungal taxa belonging to Ascomycota had higher adaptability to the stress.As the substrate was consumed with the incubation,bacterial competition intensified,but the fungal co-occurrence pattern changed weakly during decomposition.Collectively,these findings revealed the threshold effect of salinity on SOM decomposition in coastal salt marshes and emphasized that salt stress plays a key role in carbon sequestration by regulating microbial keystone taxa,metabolisms,and interactions.

Defect-density control of platinum-based nanoframes with high-index facets for enhanced electrochemical properties

Structure-engineered platinum-based nanoframes(NFs)at the atomic level can effectively improve the catalytic performance for fuel cells and other heterogeneous catalytic fields.We report herein,a microwave-assisted wet-chemical method for the preparation of platinum-copper-cobalt NFs with tunable defect density and architecture,which exhibit enhanced activity and durability towards the electro-oxidation reactions of methanol(MOR)and formic acid(FAOR).By altering the reduction/capping agents and thus the nucleation/growth kinetics,trimetallic platinum-copper-cobalt hexapod NFs with different density high-index facets are achieved.Especially,the rough hexapod nanoframes(rh-NFs)exhibit excellent specific activities towards MOR and FAOR,7.25 and 5.20 times higher than those of benchmark Pt/C,respectively,along with prolonged durability.The excellent activities of the rh-NFs are assigned to a synergistic effect,including high density of defects and high-index facets,suitable d-band center,and open-framework structure.This synergistic working mechanism opens up a new way for enhancing their electrocatalytic performances by increasing defect density and high-index facets in open-framework platinum-based NFs.

Hydroxyl radical induced from hydrogen peroxide by cobalt manganese oxides for ciprofloxacin degradation

Advanced oxidation processes(AOPs)are promising technology to remove organic pollutant in water.However,the main problem in the AOPs is the low generation of hydroxyl radical(·OH)owing to the low decomposition efficiency of hydrogen peroxide(H_(2)O_(2)).Herein,the spinel type cobalt acid manganese(MnCo_(2)O_(4))with flower morphology was fabricated through a co-precipitation method.In situ Fourier transform infrared spectroscopy confirms that the MnCo_(2)O_(4) with the optimal molar ratio of Co and Mn precursors(CM3,Co:Mn=3)has more Lewis acid sites compared with single metal oxide catalysts(Co_(3)O_(4) and Mn_(2)O_(3)),leading to the excellent performances for H_(2)O_(2) decomposition rate constant on CM3,which is about 15.03 and 4.21 times higher than those of Co_(3)O_(4) and Mn_(2)O_(3),respectively.As a result,the obtained CM3 shows a higher ciprofloxacin degradation ratio than that of Co_(3)O_(4) and Mn_(2)O_(3).Furthermore,CM3 shows an excellent stability during several cycles.This work proposes effective catalysts for ciprofloxacin decomposition and provides feasible route for treating practical environmental problems.