A mini review on recent advances in thermocatalytic hydrogenation of carbon dioxide to value-added chemicals and fuels

The development of industrialization has led to the increased demands for carbon-based energy resources, meanwhile, excessive carbon dioxide (CO_(2)) emission caused by industrialization has aroused enormous environmental concerns. With the proposal of global carbon neutrality, much attention has been paid to the thermocatalytic hydrogenation of CO_(2) into value-added chemicals and fuels, which is widely considered as a promising way to alleviate carbon emission and energy shortage. CO_(2) hydrogenation to hydrocarbons mainly undergoes a CO_(2)-modified Fischer-Tropsch synthesis (CO_(2)-FTS) route or a methanol-mediated (MeOH) route. However, each route needs to be further optimized and possesses its own advantages and disadvantages. In the present review, the mechanisms and primary intermediates of these two routes are firstly summarized. Hereafter, the current understandings of the relationship among catalytic performance, physical-chemical properties of catalysts and reaction conditions for each route are overviewed according to different target products, including light olefins, gasoline, jet fuel, diesel and aromatics. Finally, we provide an outlook of dual-pathway catalysts on future direction of CO_(2) hydrogenation.

A novel“Snowflake”--rGO-CuO for ultrasonic degradation of rhodamine and methyl orange

Graphene-doped CuO(rGO-CuO)nanocomposites with flower shapes were prepared by an improved solvothermal method.The samples were characterized by X-ray diffraction,X-ray photoelectron spectroscopy and UV–visible spectroscopy.The active species in the degradation reaction of rGO-CuO composites under ultrasonic irradiation were detected by electron paramagnetic resonance.On the basis of comparative experiments,the photodegradation mechanisms of two typical dyes,Rhodamine B(Rh B)and methyl orange(MO),were proposed.The results demonstrated that the doped CuO could improve the degradation efficiency.The catalytic degradation efficiency of rGO-CuO(2:1)to rhodamine B(RhB)and methyl orange(MO)reached 90%and 87%respectively,which were 2.1 times and 4.4 times of the reduced graphene oxide.Through the first-principles and other theories,we give the reasons for the enhanced catalytic performance of rGO-CuO:combined with internal and external factors,rGO-CuO under ultrasound could produce more hole and active sites that could interact with the OH·in pollutant molecules to achieve degradation.The rGO-CuO nanocomposite has a simple preparation process and low price,and has a high efficiency of degrading water pollution products and no secondary pollution products.It has a low-cost and high-efficiency application prospect in water pollution industrial production and life.

Recent Advances on Challenges and Strategies of Manganese Dioxide Cathodes for Aqueous Zinc-Ion Batteries

Aqueous zinc-ion batteries(AZIBs)are regarded as promising electrochemical energy storage devices owing to its low cost,intrinsic safety,abundant zinc reserves,and ideal specific capacity.Compared with other cathode materials,manganese dioxide with high voltage,environmental protection,and high theoretical specific capacity receives considerable attention.However,the problems of structural instability,manganese dissolution,and poor electrical conductivity make the exploration of high-performance manganese dioxide still a great challenge and impede its practical applications.Besides,zinc storage mechanisms involved are complex and somewhat controversial.To address these issues,tremendous efforts,such as surface engineering,heteroatoms doping,defect engineering,electrolyte modification,and some advanced characterization technologies,have been devoted to improving its electrochemical performance and illustrating zinc storage mechanism.In this review,we particularly focus on the classification of manganese dioxide based on crystal structures,zinc ions storage mechanisms,the existing challenges,and corresponding optimization strategies as well as structure-performance relationship.In the final section,the application perspectives of manganese oxide cathode materials in AZIBs are prospected.

Terahertz time-domain spectroscopy of a simulated pore structure to probe particle size and porosity of porous rock

The particle sizes and porosities of simulated pore structures are probed by terahertz time-domain spectroscopy.A double-peak time-domain spectrum phenomenon is observed when the terahertz（THz） pulses illuminated a pore and a particle. The amplitudes of the two peaks depend strongly and monotonically on the particle size and porosity. A model is used to study the phenomenon, and the computational results agreed with the experimental measurements. These measurements indicate the terahertz spectroscopic behaviors of pores and particles, suggesting that terahertz spectroscopy can be used as a noncontact probe of porosity.

New process development and process evaluation for capturing CO2 in flue gas from power plants using ionic liquid[emim][Tf2N]

Using the ionic liquid[emim][Tf2N]as a physical solvent,it was found by Aspen Plus simulation that it was possible to attempt to capture CO2 from the flue gas discharged from the coal-fired unit of the power plant.Using the combination of model calculation and experimental determination,the density,isostatic heat capacity,viscosity,vapor pressure,thermal conductivity,surface tension and solubility of[emim][Tf2N]were obtained.Based on the NRTL model,the Henry coefficient and NRTL binary interaction parameters of CO2 dissolved in[emim][Tf2N]were obtained by correlating[emim][Tf2N]with the gas–liquid equilibrium data of CO2.Firstly,the calculated relevant data is imported into Aspen Plus,and the whole process model of the ionic liquid absorption process is established.Then the absorption process is optimized according to the temperature distribution in the absorption tower to obtain a new absorption process.Finally,the density,constant pressure heat capacity,surface tension,thermal conductivity,and viscosity of[emim][Tf2N]were changed to investigate the effect of ionic liquid properties on process energy consumption,solvent circulation and heat exchanger design.The results showed that based on the composition of the inlet gas stream to the absorbers,CO2 with a capture rate of 90%and a mass purity higher than 99.5%was captured.These results indicate that the[emim][Tf2N]could be used as a physical solvent for CO2 capture from coal-fired units.In addition,the results will provide a theoretical basis for the design of new ionic liquids for CO2 capture.

Application of silver-based dihydric alcohol to the extraction of methyl linolenate with high extractability and stability replacing ionic liquids

A novel silver-based dihydric alcohol extractant was substituted for ionic liquids to enrich methyl linolenate(C18-3)from tallow seed oil methyl ester in this study.The interactions among dihydric alcohol,Ag(I)and C18-3 were explored by FT-IR spectroscopy.The effects of dihydric alcohol structure,carrier Ag(I)concentration,temperature and initial feed concentration on extraction yield and selectivity were reported.The good extraction performance was achieved by 1,4-butanediol containing AgBF4.The complexation of Ag(I)with C18-3 was dominant in extraction operation rather than physical partition.Furthermore,a multi-step reverse extraction method was proposed to obtain C18-3 product and regenerate the extractant.1-Hexene as the stripping phase can facilitate C18-3 reverse extraction.The content of C18-3 in the product was up to 93.36%,and the yield was 73.76%.This work opened a new route for the utilization of the dihydric alcohol properties to manipulate the carrier efficiency for extracting unsaturated fatty acid methyl esters at a lower cost.

Adsorption of congo red on mesoporous activated carbon prepared by CO2 physical activation

This research demonstrates the production of mesoporous activated carbon from sargassum fusiforme via physical activation with carbon dioxide.Central composite design was applied to conduct the experiments at different levels by altering three operating parameters.Activation temperature(766-934℃),CO2 flow rate(0.8-2.8 L·min^-1)and activation time(5-55 min)were the variables examined in this study.The effect of parameters on the specific surface area,total pore volume and burn-out rate of activated carbon was studied,and the influential parameters of methylene blue adsorption value were identified employing analysis of variance.The optimum conditions for maximum methylene blue adsorption value were:activation temperature=900℃,activation time=29.05 min and CO2 flow rate=1.8 L·min(-1).The activated carbon produced under optimum conditions was characterized by BET,FTIR and SEM.The adsorption behavior on congo red was studied.The effect of parameters on the adsorbent dosage,temperature,PH and initial congo red concentration was investigated.The adsorption properties of the activated carbon were investigated by kinetics.The equilibrium removal rate and maximum adsorption capacity reaches up to 94.72%,234 mg·g^-1,respectively when initial congo red concentration is 200 mg·L^-1 under adsorbent dosage(0.8 g·L^-1),temperature(30℃),PH7.

Pressure-dependent terahertz optical characterization of heptafluoropropane

Heptafluoropropane （HFP）, as the best altemative to halon fire-suppression agents, is now a widely used fire extin- guishing agent. The current studies of HFP, concentrating on the extinguishing mechanisms of flames and decomposition products, in general deal with the destructive and high temperature cases. In this paper, terahertz time-domain spectra are used to characterize HFP at different pressures. Optical parameters of HFP, such as absorption coefficient, refractive index, and relative permittivity, and their relationship with concentration of samples, are discussed. The absorption peak of HFP at 0.3 THz depends strongly on the applied pressure, and the corresponding parameters increase almost linearly with increasing HFP concentration. The present study lays a foundation for future extensive applications.

MXene Ti_(3)C_(2) decorated g-C_(3)N_(4)/ZnO photocatalysts with improved photocatalytic performance for CO_(2) reduction

Photocatalytic reduction of CO_(2) is considered as a kind of promising technologies for solving the greenhouse effect.Herein,a novel hybrid structure of g-C_(3)N_(4)/ZnO/Ti_(3)C_(2) photocatalysts was designed and fabricated to investigate their abilities for CO_(2) reduction.As demonstration,heterojunction of g-C_(3)N_(4)/ZnO can improve photogenerated carriers’separation,the addition of Ti_(3)C_(2) fragments can further facilitate the photocatalytic performance from CO_(2) to CO.Hence,g-C_(3)N_(4)/ZnO/Ti_(3)C_(2) has efficiently increased CO production by 8 and 12 times than pristine g-C_(3)N_(4) and ZnO,respectively.Which is ascribed to the photogenerated charge migration promoted by metallic Ti_(3)C_(2).This work provides a guideline for designing efficient hybrid catalysts on other applications in the renewable energy fields.

Predictive models for characterizing the atomization process in pyrolysis of methyl ricinoleate

Pyrolysis of methyl ricinoleate(MR)can produce undecylenic acid methyl ester and heptanal which are important chemicals.Atomization feeding favors the heat exchange in the pyrolysis process and hence increases the product yield.Herein,predictive models to characterize the atomization process were developed.The effect of spray distance on Sauter mean diameter(SMD)of atomized MR droplets was examined,with the optimal spray distance to be 40-50 mm.Temperature mainly affected the physical properties of feedstock,with smaller droplet size obtained at increasing temperature.In addition,pressure had significant influence on SMD and higher pressure resulted in smaller atomized droplets.Then,a model for SMD prediction,combining temperature,pressure,spray distance,and structural parameters of nozzle,was developed through dimensionless analysis.The results showed that SMD was a power function of Reynolds number(Re),Ohnesorge number(Oh),and the ratio of spray distance to diameter of swirl chamber in the nozzle(H/dsc),with the exponents of-1.6618,-1.3205 and 0.1038,respectively.The experimental measured SMD was in good agreement with the calculated values,with the error within±15%.Moreover,the droplet size distribution was studied by establishing the relationship between the standard deviation of droplet size and SMD.This study could provide reference to the regulation and optimization of the atomization process in MR pyrolysis.

Regulating solid electrolyte interphases on phosphorus/carbon anodes via localized high-concentration electrolytes for potassium-ion batteries

The resourceful and inexpensive red phosphorus has emerged as a promising anode material of potassium-ion batteries(PIBs) for its large theoretical capacities and low redox potentials in the multielectron alloying/dealloying reactions,yet chronically suffering from the huge volume expansion/shrinkage with a sluggish reaction kinetics and an unsatisfactory interfacial stability against volatile electrolytes.Herein,we systematically developed a series of localized high-concentration electrolytes(LHCE) through diluting high-concentration ether electrolytes with a non-solvating fluorinated ether to regulate the formation/evolution of solid electrolyte interphases(SEI) on phosphorus/carbon(P/C) anodes for PIBs.Benefitting from the improved mechanical strength and structural stability of a robust/uniform SEI thin layer derived from a composition-optimized LHCE featured with a unique solvation structure and a superior K+migration capability,the P/C anode with noticeable pseudocapacitive behaviors could achieve a large reversible capacity of 760 mA h g^(-1)at 100 mA g^(-1),a remarkable capacity retention rate of 92.6% over 200 cycles at 800 mA g^(-1),and an exceptional rate capability of 334 mA h g^(-1)at8000 mA g^(-1).Critically,a suppressed reduction of ether solvents with a preferential decomposition of potassium salts in anion-derived interfacial reactions on P/C anode for LHCE could enable a rational construction of an outer organic-rich and inner inorganic-dominant SEI thin film with remarkable mechanical strength/flexibility to buffer huge volume variations and abundant K+diffusion channels to accelerate reaction kinetics.Additionally,the highly reversible/durable full PIBs coupling P/C anodes with annealed organic cathodes further verified an excellent practical applicability of LHCE.This encouraging work on electrolytes regulating SEI formation/evolution would advance the development of P/C anodes for high-performance PIBs.

Infrared laser-induced fast photovoltaic effect observed in orthorhombic tin oxide film

The SnO_2/SnO with an orthorhombic structure is a material known to be stable at high pressures and temperatures and expected to have new optical and electrical properties. The authors report a new finding of the infrared laser induced a fast photovoltaic effect arising from orthorhombic tin oxide film with an indirect band gap（~2.4 e V） which is deposited by pulsed laser deposition. The rising time of the photovoltaic signal is about 3 ns with a peak value of 4.48 mV under the pulsed laser beam with energy density 0.015 m J/mm^2. The relation between the photovoltages and laser positions along the line between two electrodes of the film is also exhibited. A possible mechanism is put forward to explain this phenomenon.All data and analyses demonstrate that the orthorhombic tin oxide with an indirect band gap could be used as a candidate for an infrared photodetector which can be operated at high pressures and temperatures.

Terahertz-dependent identification of simulated hole shapes in oil gas reservoirs

Detecting holes in oil–gas reservoirs is vital to the evaluation of reservoir potential. The main objective of this study is to demonstrate the feasibility of identifying general micro-hole shapes, including triangular, circular, and square shapes, in oil–gas reservoirs by adopting terahertz time-domain spectroscopy(THz-TDS). We evaluate the THz absorption responses of punched silicon(Si) wafers having micro-holes with sizes of 20 μm–500 μm. Principal component analysis(PCA) is used to establish a model between THz absorbance and hole shapes. The positions of samples in three-dimensional spaces for three principal components are used to determine the differences among diverse hole shapes and the homogeneity of similar shapes. In addition, a new Si wafer with the unknown hole shapes, including triangular, circular, and square, can be qualitatively identified by combining THz-TDS and PCA. Therefore, the combination of THz-TDS with mathematical statistical methods can serve as an effective approach to the rapid identification of micro-hole shapes in oil–gas reservoirs.

Recent advancements and perspectives of the CO_(2)hydrogenation reaction

Owing to excessive carbon dioxide(CO_(2))emissions,which cause severe environmental issues,the conversion and utilization of CO_(2)have received increasing attention.Owing to its high efficiency and potential for industrial applications,converting CO_(2)into high value-added chemicals via thermocatalytic hydrogenation is a highly effective route among electrocatalytic,photocatalytic,and thermocatalytic CO_(2)conversion.In the past two decades,our group has developed novel CO_(2)hydrogenation technologies to produce chemicals such as aliphatic hydrocarbons,methanol(MeOH),ethanol,and aromatics(especially para-xylene,PX).In this review,we summarize the strategy for CO_(2)hydrogenation conversion and the novel rational design of catalysts,including low-temperature MeOH synthesis and capsule catalysts for tandem catalysis.We also discuss the challenges and opportunities of CO_(2)hydrogenation,such as CO_(2)capture,H2 prices,and carbon taxes.We hope to inspire new ideas for CO_(2)hydrogenation to produce high value-added chemicals through the design of catalysts and the exploration of reaction paths.

Probing the sulfur content in gasoline quantitatively with terahertz time-domain spectroscopy

Terahertz time-domain spectroscopy(THz-TDS)was used for the quantitative detection of sulfur content in gasoline.Models of chemo metrics methods and partial least squares(PLS)were built to measure THz-TDS and the sulfur content.All of the samples were divided into two parts.One part was used for calibration and the other one for validation.In order to evaluate the quality of the models,the correlation coefficient(R)and root-mean-square errors(RMSE)of calibration and validation models were calculated.The value of R and RMSE were close to 1 and 0 within acceptable levels,respectively,indicating that the combination of THz-TDS and PLS is a potential method for further quantitative detection.

Probing PM_(2.5) with terahertz wave

The goal of continuous ambient participate monitoring has been accomplished by the use of terahertz （THz） wave. The fre- quency-dependent spectrum and absorbance of the particulate matter （PM2.5） were measured in the range of 0-10 THz. The PM2.5 concentration ,o was calculated according to the sampling time and air flow. With the increase of ,o, the THz wave am- plitude gradually decreased and the absorbance A of PM2.5 increased. The relationship between p and A can be described mathematically through p∝ A0.5. Our results demonstrate that the terahertz wave could be a valuable tool to monitor and in- spect the PM2.5 concentration.

Double-peaked decay of transient photovoltage in nanoporous ZnO/n-Si photodetector

In the present work,a nanoporous ZnO/n-Si structure has been proposed as a new type infrared photodetector.Triggered by one laser pulse with wavelength of 1064 nm,this structure exhibits a double-peak decay of transient photovoltage.Also,the time interval between these two peaks increases linearly with the increase of irradiated pulsed energy,indicating the promising application of this hetero-junction in photo-energy detection of infrared pulsed laser.A possible mechanism for this particular photoresponse has been discussed.

Detecting NO3- concentration in nitrate solutions using terahertz time-domain spectroscopy

In this paper, we employed terahertz time domain spectroscopy （THz-TDS） to investigate the nitrate 0 concentration in four types of nitrate solution （sodium nitrate, aluminum nitrate, calcium nitrate and magnesium nitrate）. Their absorption coefficient and refractive index were calculated in 0.2-2.5THz, and a logarithmic relationship was observed between NO3 concentrations and selected optical parameters regardless of the kinds of nitrate solution. Partial least square （PLS） model was built between THz-TDS and NO3 concentration. The correlation coefficient of PLS model was calculated. The results make the quantitative analysis of NO3 concentration possible by THz-TDS and indicate the bright future in practical application.

Revealing interaction of pyridinic N in N-doped carbon with Sn sites for improved CO_(2)reduction

N-doped carbon(NC)materials have emerged as attractive supports for metal-based catalysts,enhancing their catalytic performance through the metal-support interactions.However,gaining fundamental insights into the metalsupport interaction between NC support and Sn metal sites for improving the electrocatalytic CO_(2)reduction reaction(CO_(2)RR)performance remains challenging.