Ultrafine ordered L1_(2)-Pt-Co-Mn ternary intermetallic nanoparticles as high-performance oxygen-reduction electrocatalysts for practical fuel cells

The long-range periodically ordered atomic structures in intermetallic nanoparticles(INPs)can significantly enhance both the electrocatalytic activity and electrochemical stability toward the oxygen reduction reaction(ORR)compared to the disordered atomic structures in ordinary solid-solution alloy NPs.Accordingly,through a facile and scalable synthetic method,a series of carbon-supported ultrafine Pt_3Co_(x)Mn_(1-x)ternary INPs are prepared in this work,which possess the"skin-like"ultrathin Pt shells,the ordered L1_(2) atomic structure,and the high-even dispersion on supports(L1_(2)-Pt_3Co_(x)Mn_(1-x)/~SPt INPs/C).Electrochemical results present that the composition-optimized L1_(2)-Pt_3Co_(0.7)Mn_(0.3)/~SPt INPs/C exhibits the highest electrocata lytic activity among the series,which are also much better than those of the pristine ultrafine Pt/C.Besides,it also has a greatly enhanced electrochemical stability.In addition,the effects of annealing temperature and time are further investigated.More importantly,such superior ORR electrocatalytic performance of L1_(2)-Pt_3Co_(0.7)Mn_(0.3)/~SPt INPs/C are also well demonstrated in practical fuel cells.Physicochemical characterization analyses further reveal the major origins of the greatly enhanced ORR electrocata lytic performance:the Pt-Co-Mn alloy-induced geometric and ligand effects as well as the extremely high L1_(2) atomic-ordering degree.This work not only successfully develops a highly active and stable ordered ternary intermetallic ORR electrocatalyst,but also elucidates the corresponding"structure-function"relationship,which can be further applied in designing other intermetallic(electro)catalysts.

An optimized smearing scheming for first Brillouin zone sampling and its application on thermal conductivity prediction of graphite

We propose an optimized scheme to determine the smearing parameter in the Gaussian function that is used to replace the Dirac δ function in the first Brillouin zone sampling. The broadening width is derived by analyzing the difference of the results from the phase-space method and Gaussian broadening method. As a demonstration, using the present approach,we investigate the phonon transport in a typical layered material, graphite. Our scheme is benchmarked by comparing with other zone sampling methods. Both the three-phonon phonon scattering rates and thermal conductivity are consistent with the prediction from the widely used tetrahedron method and adaptive broadening method. The computational efficiency of our scheme is more than one order of magnitude higher than the two other methods. Furthermore, the effect of fourphonon scattering in phonon transport in graphite is also investigated. It is found that four-phonon scattering reduces the through-plane thermal conductivity by 10%. Our methods could be a reference for the prediction of thermal conductivity of anisotropic material in the future.

Visible-light driven room-temperature coupling of methane to ethane by atomically dispersed Au on WO_(3)

Gold(Au)as co-catalyst is remarkable for activating methane(CH4),especially atomically dispersed Au with maximized exposing active sites and specific electronic structure.Furthermore,singlet oxygen(^(1)O_(2))typically manifests a mild redox capacity with a high selectivity to attack organic substrates.Peroxomonosulfate(PMS)favors to produce oxidative species 102 during the photocatalytic reactions.Thus,combining atomic Au as co-catalyst and ^(1)O_(2) as oxidant is an effective strategy to selectively convert CH4.Herein,we synthesized atomically dispersed Au on WO_(3)(Au/WO_(3)),where Au was in the forms of single atoms and clusters.At room temperature,such Au/WO_(3) exhibited enhanced photocata lytic conversion of CH4 to CH3 CH3 with a selectivity,up to 94%,under visible light.The radicals-pathway mechanism of CH4 coupling has also been investigated through detection and trapping experiment of active species.Theoretical calculations further interpret the electronic structure of Au/WO_(3) and tip-enhanced local electric field at the Au sites for promoting CH4 conversion.

Stabilizing the MAPbI3 perovksite via the in-situ formed lead sulfide layer for efficient and robust solar cells

Surface passivation via post-treatment with organic reagents is a popular strategy to improve the stability and efficiency of perovskite solar cell. However, organic passivation still suffers from the weak bonding between organic chemicals and perovskite layers. Here we reported a facile inorganic layer passivating method containing strong Pb–S bonding by using ammonium sulfide treatment. A compact PbS_x layer was in-situ formed on the top surface of the perovskite film, which could passivate and protect the perovskite surface to enhance the performance and stability. Our novel inorganic passivation layer strategy demonstrates great potential for the development of high efficiency hybrid and robust perovskite optoelectronics.

Machine learning-based ionic liquids design and process simulation for CO_(2) separation from flue gas

Rational design of ionic liquids(ILs),which is highly dependent on the accuracy of the model used,has always been crucial for CO_(2)separation from flue gas.In this study,a support vector machine(SVM)model which is a machine learning approach is established,so as to improve the prediction accuracy and range of IL melting points.Based on IL melting points data with 600 training data and 168 testing data,the estimated average absolute relative deviations(AARD)and squared correlation coefficients(R^(2))are 3.11%,0.8820 and 5.12%,0.8542 for the training set and testing set of the SVM model,respectively.Then,through the melting points model and other rational design processes including conductor-like screening model for real solvents(COSMO-RS)calculation and physical property constraints,cyano-based ILs are obtained,in which tetracyanoborate[TCB]-is often ruled out due to incorrect estimation of melting points model in the literature.Subsequently,by means of process simulation using Aspen Plus,optimal IL are compared with excellent IL reported in the literature.Finally,1-ethyl-3-methylimidazolium tricyanomethanide[EMIM][TCM]is selected as a most suitable solvent for CO_(2)separation from flue gas,the process of which leads to 12.9%savings on total annualized cost compared to that of 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)amide[EMIM][Tf_(2)N].

RP-3航空煤油高压共轨喷射特性的实验研究

RP-3航空煤油可以作为替代燃料应用于柴油发动机。本文研究了RP-3航空煤油在单次喷射和多次喷射策略下的喷射特性,并与柴油燃料的喷射特性进行对比。实验结果表明,尽管RP-3航空煤油的喷射延迟时间比柴油短,但该差异在实际发动机运行工况中可以忽略。此外,虽然RP-3航空煤油较低的密度和黏度导致其更高的体积喷射速率和循环喷射量,然而,RP-3航空煤油的循环质量喷射量和质量喷射速率接近或略低于柴油。基于两种燃料的喷射特性对比,可以发现燃料的物理性质在单次喷射和多次喷射策略中是影响燃料喷射特性的次要因素。

Synergistic stabilization of CsPbI_(3) inorganic perovskite via 1D capping and secondary growth

Cesium lead iodide(CsPbI_(3)) perovskite has gained great attention in the photovoltaic(PV) community because of its unique optoelectronic properties, good chemical stability and appropriate bandgap for sunlight harvesting applications. However, compared to solar cells fabricated from organic-inorganic hybrid perovskites, the commercialization of devices based on all-inorganic CsPbI_(3) perovskites still faces many challenges regarding PV performance and long-term stability. In this work, we discovered that tetrabutylammonium bromide(TBABr) post-treatment to CsPbI_(3) perovskite films could achieve synergistic stabilization with both TBA+cation intercalation and Br-doping. Such TBA^(+) cation intercalation leads to onedimensional capping with TBAPb I3 perovskite formed in situ, while the Br-induced crystal secondary growth helps effectively passivate the defects of CsPbI_(3) perovskite, thus enhancing the stability. In addition, the incorporation of TBABr can improve energy-level alignment and reduce interfacial charge recombination loss for better device performance. Finally, the highly stable TBABr-treated CsPbI_(3)-based perovskite solar cells show reproducible photovoltaic performance with a champion efficiency up to 19.04%, while retaining 90% of the initial efficiency after 500 h storage without encapsulation.

Molecular simulation on carbon dioxide capture performance for carbons doped with various elements

Among the different types of CO_(2)capture technologies for post-combustion,sorption CO_(2)capture technology with carbon-based sorbents have been extensively explored with the purpose of enhancing their sorption perfor-mance by doping hetero elements due to the rapid reaction kinetics and low costs.Herein,sorption capacity and selectivity for CO_(2)and N 2 on carbon-based sorbents doped with elements such as nitrogen,sulfur,phosphorus,and boron,are evaluated and compared using the grand canonical Monte Carlo(GCMC)method,the universal force field(UFF),and transferable potentials for phase equilibria(TraPPE).The sorption capacities of N-doped porous carbons(PCs)at 50℃were 76.1%,70.7%,50.6%,and 35.7%higher than those of pure PCs,S-doped PCs,P-doped PCs,and B-doped PCs,respectively.Its sorption selectivity at 50℃was approximately 14.0,nearly twice that of pure PCs or other hetero-element-doped PCs.The N-doped PCs showed the largest sorption heat at 50℃among all the PCs,approximately 20.6 kJ·mol^(−1),which was 9.7%−25.5%higher than that of the pure PCs under post-combustion conditions.Additionally,with the product purity of 41.7 vol.%−75.9 vol.%for vacuum pressure swing sorption,and 53.4 vol.%−83.6 vol.%for temperature swing sorption,the latter is more suitable for post-combustion conditions than pressure-swing sorption.

Frontier science and challenges on offshore carbon storage

Carbon capture and storage(CCS)technology is an imperative,strategic,and constitutive method to considerably reduce anthropogenic CO_(2)emissions and alleviate climate change issues.The ocean is the largest active carbon bank and an essential energy source on the Earth's surface.Compared to oceanic nature-based carbon dioxide removal(CDR),carbon capture from point sources with ocean storage is more appropriate for solving short-term climate change problems.This review focuses on the recent state-of-the-art developments in offshore carbon storage.It first discusses the current status and development prospects of CCS,associated with the chailenges and uncertainties of oceanic nature-based CDR.The second section outlines the mechanisms,sites,advantages,and ecologic hazards of direct offshore CO_(2)injection.The third section emphasizes the mechanisms,schemes,influencing factors,and recovery efficiency of ocean-based CO-CH_(4)replacement and CO_(2)-enhanced oil recovery are reviewed.In addition,this review discusses the economic aspects of offshore CCS and the preponderance of offshore CCs hubs.Finally,the upsides,limitations,and prospects for further investigation of offshore CO_(2)storage are presented.

光驱动Rh/InGaN_(1-x)O_(x)纳米组装体甲烷干重整制合成气

Light-driven dry reforming of methane toward syngas presents a proper solution for alleviating climate change and for the sustainable supply of transportation fuels and chemicals.Herein,Rh/InGaN_(1-x)O_(x) nanowires supported by silicon wafer are explored as an ideal platform for loading Rh nanoparticles,thus assembling a new nanoarchitecture for this grand topic.In combination with the remarkable photothermal synergy,the O atoms in Rh/InGaN_(1-x)O_(x) can significantly lower the apparent activation energy of dry reforming of methane from 2.96 eV downward to 1.70 eV.The as-designed Rh/InGaN_(1-x)O_(x) NWs nanoarchitecture thus demonstrates a measurable syngas evolution rate of 180.9 mmol g_(cat)^(-1) h^(-1) with a marked selectivity of 96.3% under concentrated light illumination of 6 W cm^(-2).What is more,a high turnover number(TON)of 4182 mol syngas per mole Rh has been realized after six reuse cycles without obvious activity degradation.The correlative 18O isotope labeling experiments,in-situ irradiated X-ray photoelectron spectroscopy(ISI-XPS)and in-situ diffuse reflectance Fourier transform infrared spectroscopy characterizations,as well as density functional theory calculations reveal that under light illumination,Rh/InGaN_(1-x)O_(x) NWs facilitate releasing^(*)CH_(3) and H^(+)from CH_(4) by holes,followed by H_(2) evolution from H^(+)reduction with electrons.Subsequently,the O atoms in Rh/InGaN_(1-x)O_(x) can directly participate in CO generation by reacting with the ^(*)C species from CH_(4) dehydrogenation and contributes to the coke elimination,in concurrent formation of O vacancies.The resultant O vacancies are then replenished by CO_(2),showing an ideal chemical loop.This work presents a green strategy for syngas production via light-driven dry reforming of methane.

Photocatalytic reduction of carbon dioxide by titanium oxide- based semiconductors to produce fuels

To tackle the crisis of global warming, it is imperative to control and mitigate the atmospheric carbon dioxide level. Photocatalytic reduction of carbon dioxide into solar fuels furnishes a gratifying solution to utilize and reduce carbon dioxide emission and simultaneously generate renewable energy to sustain the societies. So far, titanium oxide-based semiconductors have been the most prevalently adopted catalysts in carbon dioxide photoreduction. This mini-review provides a general summary of the recent progresses in titanium oxide- catalyzed photocatalytic reduction of carbon dioxide. It first illustrates the use of structural engineering as a strategy to adjust and improve the catalytic performances. Then, it describes the introduction of one/two exogenous elements to modify the photocatalytic activity and/or selectivity. Lastly, it discusses multi-component hybrid titanium oxide composites.

Toward carbon neutrality:Uncovering constraints on critical minerals in the Chinese power system

China has set up its ambitious carbon neutrality target,which mainly relies on significant energy-related carbon emissions reduction.As the largest important contributing sector,power sector must achieve energy transition,in which critical minerals will play an essential role.However,the potential supply and demand for these minerals are uncertain.This study aims to predict the cumulative demand for critical minerals in the power sector under different scenarios via dynamic material flow analysis(DMFA),including total demands,supplies and production capacities of different minerals.Then,these critical minerals are categorized into superior and scarce resources for further analysis so that more detailed results can be obtained.Results present that the total minerals supply will not meet the total minerals demand(74260 kt)in 2060.Serious resource shortages will occur for several key minerals,such as Cr,Cu,Mn,Ag,Te,Ga,and Co.In addition,the demand for renewable energy will be nearly fifty times higher than that of fossil fuels energy,implying more diversified demands for various minerals.Finally,several policy recommendations are proposed to help improve the overall resource efficiency,such as strategic reserves,material substitutions,and circular economy.

Stable Combustion under Carbon Dioxide Enriched Methane Blends For Exhaust Gas Recirculation(EGR)

Exhaust gas recirculation(EGR)is one of the main techniques to enable the use of oxyfuel combustion for carbon capture and storage(CCS).However,the use of recirculated streams with elevated carbon dioxide poses different challenges.Thus,more research is required about the cumulative effects on the desirable outcomes of the combustion processes such as thermal efficiency,reduced emissions and system operability,when fuels with high CO_(2) concentration for CCS exhaust gas recirculation or biogas are used.Therefore,this study evaluates the use of various CO_(2) enriched methane blends and their response towards the formation of a great variety of structures that appear in swirling flows,which are the main mechanism for combustion control in current gas turbines systems.The study uses 100 kW acoustically excited swirl-stabilised burner to investigate the flow field response to the resultant effects of the variation in the swirl strength,excitation under isothermal condition and the corresponding effects during combustion with different fuels at various CO_(2) concentrations.Results show changes in size and location of flow structures as a result of the changes in the mean and turbulent velocities of the flow field,consequence of the imposition of different swirl and forcing conditions.Improved thermal efficiency is also observed in the system when using high swirl and forcing while the blend of CO_(2) with methane balanced the heat release fluctuation with a corresponding reduction in the acoustic amplitudes of the combustion response,suggesting that certain CO_(2) concentrations in the fuel can provide more stable flames.Concentrations between 10%to 15%CO_(2) volume show great promise for stability improvement,with the potential of using these findings in larger units that employ CCS technologies.

China’s energy transitions for carbon neutrality:challenges and opportunities

The pledge of achieving carbon peak before 2030 and carbon neutrality before 2060 is a strategic decision that responds to the inherent needs of China’s sustainable and high-quality development,and is an important driving force for promoting China’s ecological civilization constructions.As the consumption of fossil fuel energy is responsible for more than 90%of China’s greenhouse gases emissions,policies focusing on energy transition are vital for China accomplishing the goal of carbon neutrality.Considering the fact that China’s energy structure is dominated by fossil fuels,especially coal,it is urgent to accelerate the low-carbon transition of the energy system in a relatively short time,and dramatically increase the proportion of clean energy in the future energy supply.Although China has made notable progress in the clean energy transition in the past,its path to carbon neutrality still faces many significant challenges.During the process of energy transformation,advanced technologies and greater investment will play essential parts in this extensive and profound systemic reform for China’s economy and society.In the meantime,these changes will create immense economic opportunities and geopolitical advantages.

Target the neglected VOCs emission from iron and steel industry in China for air quality improvement

Recent years have witnessed significant improvement in China’s air quality.Strict environmental protection measures have led to significant decreases in sulfur dioxide(SO2),nitrogen oxides(NOx),and particulate matter(PM)emissions since 2013.But there is no denying that the air quality in 135 cities is inferior to reaching the Ambient Air Quality Standards(GB 3095–2012)in 2020.In terms of temporal,geographic,and historical aspects,we have analyzed the potential connections between China’s air quality and the iron and steel industry.The non-target volatile organic compounds(VOCs)emissions from iron and steel industry,especially from the iron ore sinter process,may be an underappreciated index imposing a negative effect on the surrounding areas of China.Therefore,we appeal the authorities to pay more attention on VOCs emission from the iron and steel industry and establish new environmental standards.And different iron steel flue gas pollutants will be eliminated concurrently with the promotion and application of new technology.

GaN nanowires/Si photocathodes for CO_(2) reduction towards solar fuels and chemicals: advances, challenges, and prospects

Photoelectrocatalytic(PEC)production of fuels and chemicals by using solar energy,water,and CO_(2) paves a promising avenue toward carbon neutrality.Over the past decades,for accelerating this process,a variety of photocathodes have been explored.Among them,the hybrid of GaN nanowires(NWs)and planar silicon has appeared as a disruptive platform for this grand topic,owing to their distinctive structural,optoelectronic,and catalytic properties.This review illustrates the most recent advances in GaN NWs/Si-based photocathodes for CO_(2) reduction reactions powered by simulated sunlight,beginning with a discussion of the critical requirements and fundamental challenges of PEC CO_(2) reduction.The characteristics of GaN NWs/Si are then discussed,showing its great potential in precisely controlling the behavior of photons,charges,and chemical species.As the focus of this review,the progress on the PEC CO_(2) reduction reactions toward different products over GaN NWs/Si-based photocathodes is highlighted.In the end,the challenges and prospects of GaN NWs/Si-based photocathodes for the practical synthesis of solarfuels and chemicals are proposed.

Dual Phase Renewable Fuel Combustion in an Atmospheric Gas Turbine Burner

Expanding the fuel flexibility of continuous combustion systems to include multiphase fuel combustion offers additional support to combat the problem of energy security and,potentially,environmental pollution.In this study,apart from establishing stability limits and measuring post-combustion emissions,flames generated from simultaneous combustion of biodiesel and syngas were examined using C_(2)*and CH*chemiluminescence imaging to capture changes in the reaction zone.The proportion of syngas in the fuel mix was varied from 0 to 30%content(by energy contribution)while maintaining a total power output of 15 kW.The overall equivalence ratio was held at 0.7 in cases other than for determining the flammability range.The results indicate a reduction of stability limits as gas proportion in fuel blend increases.Also,chemiluminescence imaging of the two targeted species suggest a general reduction in reaction rate as well as reaction zone area and length with increase in gas ratio in the dual phase tests.Furthermore,emissions performance in the context of NOxand CO was investigated as liquid-to-gas ratios were altered.Conclusively,the study demonstrates the feasibility,limitations and potential benefits of multiphase renewable fuel combustion in a swirl-stabilised burner.

Exploring high thermal conductivity polymers via interpretable machine learning with physical descriptors

The efficient and economical exploitation of polymers with high thermal conductivity(TC)is essential to solve the issue of heat dissipation in organic devices.Currently,the experimental preparation of functional polymers with high TC remains a trial-and-error process due to the multi-degrees of freedom during the synthesis and characterization process.Polymer informatics equips machine learning(ML)as a powerful engine for the efficient design of polymers with desired properties.However,available polymer TC databases are rare,and establishing appropriate polymer representation is still challenging.In this work,we propose a high-throughput screening framework for polymer chains with high TC via interpretable ML and physical feature engineering.The hierarchical down-selection process stepwise optimizes the 320 initial physical descriptors to the final 20 dimensions and then assists the ML models to achieve a prediction accuracy R2 over 0.80,which is superior to traditional graph descriptors.Further,we analyze the contribution of the individual descriptors to TC and derive the explicit equation for TC prediction using symbolic regression.The high TC polymer structures are mostlyπ-conjugated,whose overlapping p-orbitals enable easy maintenance of strong chain stiffness and large group velocities.Ultimately,we establish the connections between the individual chains and the amorphous state of polymers.Polymer chains with high TC have strong intra-chain interactions,and their corresponding amorphous systems are favorable for obtaining a large radius of gyration and causing enhanced thermal transport.The proposed data-driven framework should facilitate the theoretical and experimental design of polymers with desirable properties.

Evidence of aircraft activity impact on local air quality: A study in the context of uncommon airport operation

Wuhan Tianhe International Airport (WUH) was suspended to contain the spread of COVID-19,while Shanghai Hongqiao International Airport (SHA) saw a tremendousflight reduction.Closure of a major international airport is extremely rare and thus represents a unique opportunity to straightforwardly observe the impact of airport emissions on local air quality.In this study,a series of statistical tools were applied to analyze the variations in air pollutant levels in the vicinity of WUH and SHA.The results of bivariate polar plots show that airport SHA and WUH are a major source of nitrogen oxides.NOx,NO_(2)and NO diminished by 55.8%,44.1%,76.9%,and 40.4%,33.3% and 59.4% during the COVID-19 lockdown compared to those in the same period of 2018 and 2019,under a reduction in aircraft activities by 58.6%and61.4%.The concentration of NO_(2),SO_(2)and PM_(2.5)decreased by 77.3%,8.2%,29.5%,right after the closure of airport WUH on 23 January 2020.The average concentrations of NO,NO_(2)and NOxscatter plots at downwind of SHA after the lockdown were 78.0%,47.9%,57.4%and 62.3%,34.8%,41.8%lower than those during the same period in 2018 and 2019.However,a significant increase in O_(3)levels by 50.0% and 25.9%at WUH and SHA was observed,respectively.These results evidently show decreased nitrogen oxides concentrations in the airport vicinity due to reduced aircraft activities,while amplified O_(3)pollution due to a lower titration by NO under strong reduction in NOxemissions.

Additives enhancing supported amines performance in CO_(2)capture fromair

The utilization of supported amines as adsorbents in direct air capture(DAC)has been demonstrated to be a promising strategy for the reduction of CO_(2)emissions.To improve the performance of amine-based adsorbents,the incorporation of additives has been widely adopted.In the present study,we conduct a comprehensive comparison of seven additives on tetraethylenepentamine-impregnated mesoporous silica as a representative amine-based adsorbent.The results indicate thatminor molecularweight additiveswith hydroxyl groups show improved adsorption-desorption performance and increase oxidative stability.A proposed mechanism for these improvements is the combined physical and chemical promotion effects of hydroxyl groups.Through a comprehensive review of existing literature,it is found that the effects of additives on amine-based adsorbents are dependent on factors,such as additive type,pristine adsorbent properties,incorporation method,and testing conditions.Based on these findings,it is recommended that future DAC systems prioritize the use of hydroxyl-containing additives,whereas higher CO_(2)concentration and temperature capture may benefit from the incorporation of additives without hydroxyl groups.These conclusions are expected to contribute to the design of efficient adsorbents for CO_(2)capture.