Colloidal quantum dots (QDs) consisting of precious‐metal‐free elements show attractive potentials towards solar‐driven CO2 reduction. However, the inhibition of hydrogen (H2) production in aqueous ...solution remains a challenge. Here, we describe the first example of a carbon–carbon (C−C) coupling reaction to block the competing H2 evolution in photocatalytic CO2 reduction in water. In a specific system taking ZnSe QDs as photocatalysts, the introduction of furfural can significantly suppress H2 evolution leading to CO evolution with a rate of ≈5.3 mmol g−1 h−1 and a turnover number (TON) of >7500 under 24 h visible light. Meanwhile, furfural is upgraded to the self‐coupling product with a yield of 99.8 % based on the consumption of furfural. Mechanistic insights show that the reductive furfural coupling reaction occurs on surface Zn‐sites to consume electrons and protons originally used for H2 production, while the CO formation pathway at surface anion vacancies from CO2 remains.
Reductive carbon–carbon coupling was used to block H2 evolution in CO2 photoreduction in water. Furfural, one of the biomass platform molecules, adsorbs on Zn‐sites consuming electrons and protons originally used for H2 production, but the CO formation pathway at surface anion vacancies remains. Therefore, CO was evolved with a CO/H2 ratio of 265 : 1 in the gas phase and furfural was upgraded to value‐added hydrofuroin.
In practical applications, particularly in flexible manufacturing systems, there is a high level of uncertainty. A type-2 fuzzy logic system (T2FS) has several parameters and an enhanced ability to ...handle high levels of uncertainty. This article proposes an improved artificial immune system (IAIS) algorithm to solve a special case of the flexible job shop scheduling problem (FJSP), where the processing time of each job is a nonsymmetric triangular interval T2FS (IT2FS) value. First, a novel affinity calculation method considering the IT2FS values is developed. Then, four problem-specific initialization heuristics are designed to enhance both quality and diversity. To enhance the exploitation abilities, six local search approaches are conducted for the routing and scheduling vectors, respectively. Next, a simulated annealing method is embedded to accept antibodies with low affinity, which can enhance the exploration abilities of the algorithm. Moreover, a novel population diversity heuristic is presented to eliminate antibodies with high crowding values. Five efficient algorithms are selected for a detailed comparison, and the simulation results demonstrate that the proposed IAIS algorithm is effective for IT2FS FJSPs.
Inspired by green plants, artificial photosynthesis has become one of the most attractive approaches toward carbon dioxide (CO2) valorization. Semiconductor quantum dots (QDs) or dot‐in‐rod (DIR) ...nano‐heterostructures have gained substantial research interest in multielectron photoredox reactions. However, fast electron–hole recombination or sluggish hole transfer and utilization remains unsatisfactory for their potential applications. Here, the first application of a well‐designed ZnSe/CdS dot‐on‐rods (DORs) nano‐heterostructure for efficient and selective CO2 photoreduction with H2O as an electron donor is presented. In‐depth spectroscopic studies reveal that surface‐anchored ZnSe QDs not only assist ultrafast (≈2 ps) electron and hole separation, but also promote interfacial hole transfer participating in oxidative half‐reactions. Surface photovoltage (SPV) spectroscopy provides a direct image of spatially separated electrons in CdS and holes in ZnSe. Therefore, ZnSe/CdS DORs photocatalyze CO2 to CO with a rate of ≈11.3 µmol g−1 h−1 and ≥85% selectivity, much higher than that of ZnSe/CdS DIRs or pristine CdS nanorods under identical conditions. Obviously, favored energy‐level alignment and unique morphology balance the utilization of electrons and holes in this nano‐heterostructure, thus enhancing the performance of artificial photosynthetic solar‐to‐chemical conversion.
A dot‐on‐rod (DOR) nano‐heterostructure is rationally constructed by anchoring multiple ZnSe QDs on a single CdS nanorod. Due to the favored energy level alignment and the good exposure of ZnSe to the surrounding medium, ultrafast (≈2 ps) charge separation and facile hole utilization are realized, which enable effective and selective CO2‐to‐CO photoreduction taking H2O as an electron donor.
Ultrafast‐response (20 μs) UV detectors, which are visible‐blind and self‐powered, in devices where an n‐type ZnO nanowire partially lies on a p‐type GaN film, are demonstrated. Moreover, a ...CdSe‐nanowire red‐light detector powered by a nanoscale ZnO/GaN photovoltaic cell is also demonstrated, which extends the device function to a selective multiwavelength photodetector and shows the function of an optical logical AND gate.
Facile activation and conversion of small molecules (e.g., H
O, CO
, N
, CH
, and C
H
) into solar fuels or value-added chemicals under mild conditions is an attractive pathway in dealing with the ...worldwide appeal of energy consumption and the growing demand of industrial feedstocks. Compared with conventional thermo- or electro-catalytic approaches, the protocol of photocatalysis shines light on green and low-cost storage of sunlight in chemical bonds. For instance, artificial photosynthesis is an effective way to split H
O into molecular O
and H
, thereby storing solar energy in the form of hydrogen fuel. Because of rational tunability in band gaps, charge-carrier dynamics, exposed active sites and catalytic redox activities by tailoring size, composition, morphology, surface, and/or interface property, semiconductor nanocrystals (NCs) emerge as very promising candidates for photo-induced small molecule activation, including H
O splitting, CO
reduction, N
fixation, CH
conversion and chemical bond formation (e.g., S-S, C-C, C-N, C-P, C-O). In this review, we summarize the recent advances in small molecule activation via artificial photosynthesis using semiconductor NCs, especially those consisting of II-VI and III-V elements. Moreover, we highlight the intrinsic advantages of semiconductor NCs in this field and look into the fabrication of prototype devices for large-scale and sustainable small molecule activation to store solar energy in chemical bonds.
Rising CO
concentration, a driving force of climate change, is impacting global food security by affecting plant physiology. Nevertheless, the effects of elevated CO
on primary and secondary ...metabolism in tea plants (Camellia sinensis L.) still remain largely unknown. Here we showed that exposure of tea plants to elevated CO
(800 µmol mol
for 24 d) remarkably improved both photosynthesis and respiration in tea leaves. Furthermore, elevated CO
increased the concentrations of soluble sugar, starch and total carbon, but decreased the total nitrogen concentration, resulting in an increased carbon to nitrogen ratio in tea leaves. Among the tea quality parameters, tea polyphenol, free amino acid and theanine concentrations increased, while the caffeine concentration decreased after CO
enrichment. The concentrations of individual catechins were altered differentially resulting in an increased total catechins concentration under elevated CO
condition. Real-time qPCR analysis revealed that the expression levels of catechins and theanine biosynthetic genes were up-regulated, while that of caffeine synthetic genes were down-regulated in tea leaves when grown under elevated CO
condition. These results unveiled profound effects of CO
enrichment on photosynthesis and respiration in tea plants, which eventually modulated the biosynthesis of key secondary metabolites towards production of a quality green tea.
Utilization of photochromism in photo-switchable white-light emitters (WLEs) is a challenging task. In an effort to achieve this, we have recently developed a new Gd-MOF using a photoactive ...pyridinium-based inner salt. The compound shows interesting photoswitchable bluish white light to greenish yellow light emission as a result of electron transfer, a phenomenon that has not been observed previously in photochromic crystal compounds.
A new Gd-MOF exhibits interesting properties of photoswitchable bluish white light to greenish yellow light emission as a result of electron transfer (ET). Photoluminescence studies on the dual-emitter Gd-MOF, which paves the way for white emission though ET.
The compression of the industrialization process has forced China to confront the double pressure of greenhouse gas emissions and air pollution. This paper constructs an energy system optimization ...model for China’s power industry; establishes four energy consumption scenarios with different constraints; and forecasts and analyses the energy consumption structure, power consumption demand and production composition of China’s power industry from 2020 to 2050. Furthermore, based on synergistic effects, the emission characteristics, emission reduction potential and costs of CO2 and air pollutants are quantitatively analysed, and the obtained synergistic emission reduction effect and influencing factors are decomposed based on technical effect and structural effect. Finally, a low-carbon emission reduction path that can realize the synergistic control of CO2 and traditional air pollutants in China’s power industry is obtained. The results show that in the future, China’s power industry will continue to grow at a greater rate than primary energy consumption and the focus of power demand will gradually shift from industry to transportation and construction. The power industry can introduce and maximize the application of optimal control technologies while optimizing the energy consumption structure in order to realize synergistic emission reduction for CO2 and traditional air pollutants in China’s power industry. While saving energy, the corresponding cost of emission reduction will remain relatively low. After CO2 emissions peak in the power industry, the main way to reduce CO2 emissions will be to optimize the structure and upgrade the technology for CO2 self-governance. For the reduction of air pollutants, the promotion effect is limited only by the implementation and promotion of structural emission reduction measures focused on non-fossil energy.
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•A bottom-up energy system optimization model for China’s electric power industry.•Energy consumption scenarios with different constraints.•Synergistic control path by structure optimization and control technology upgrading.•Emissions characteristics, reduction potential and cost are quantitatively analysed.•Synergistic emission reduction effect and influencing factors are decomposed.
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•The optimal chiller loading problem by minimizing energy consumption is investigated.•The strategy of local search around the elite weed of IWO algorithm is developed.•Detailed ...experiments have been conducted for the parameter tuning.•The experimental results show that the EIWO algorithm can find optimal solution.•The convergence ability, stability and robustness of EIWO algorithm are verified.
In this study, an improved invasive weed optimization (EIWO) algorithm is investigated to solve the optimal chiller loading (OCL) problem for minimization of the power consumption. In the proposed algorithm, several components are developed, such as decimal-based representation, reproduction approach, spatial dispersal method, and competitive selection mechanism. Then, the local search strategy for elite weed is proposed, which can improve the searching ability of the algorithm. To verify the efficiency and effectiveness of the proposed algorithm, three well-known instances based on the OCL problem in air-conditioning systems are tested with the comparison with other recently published algorithms. The experimental results show that the EIWO algorithm can find equal or better optimal solution compared with other algorithms. The convergence ability, stability and robustness are also verified after the detailed comparisons.
Perovskite solar cells are strong competitors for silicon-based ones, but suffer from poor long-term stability, for which the intrinsic stability of perovskite materials is of primary concern. ...Herein, we prepared a series of well-defined cesium-containing mixed cation and mixed halide perovskite single-crystal alloys, which enabled systematic investigations on their structural stabilities against light, heat, water, and oxygen. Two potential phase separation processes are evidenced for the alloys as the cesium content increases to 10% and/or bromide to 15%. Eventually, a highly stable new composition, (FAPbI3)0.9(MAPbBr3)0.05(CsPbBr3)0.05, emerges with a carrier lifetime of 16 μs. It remains stable during at least 10 000 h water–oxygen and 1000 h light stability tests, which is very promising for long-term stable devices with high efficiency. The mechanism for the enhanced stability is elucidated through detailed single-crystal structure analysis. Our work provides a single-crystal-based paradigm for stability investigation, leading to the discovery of stable new perovskite materials.
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