This review highlights recent advances in CO 2 photocatalytic reduction using polyoxometalate composites (MOFs/g-C 3 N 4 /LDHs), offering insights to optimize performance.
Read moreAbstract The development of efficient direct air capture (DAC) systems coupled with photocatalytic CO 2 conversion is still an appealing challenge. Here, we engineered a series of defective Cu 3 ‐based metal–organic frameworks (Cu 3 ‐MOFs) for integrated atmospheric CO 2 capture and in situ photoreduction. The defective Cu 3 ‐MOFs were constructed through selective removal of coordinated CO 3 2− from pristine MOFs with HCl etching, generating unsaturated Cu active sites for CO 2 harvesting, and the Cu 3 ‐MOFs demonstrated enhanced CO 2 capture kinetics and capacity that compared to their pristine counterpart. Remarkably, the captured CO 2 could be directly photoreduced to C 2 H 4 with an optimal production rate of 18.25 µmol·g −1 ·h −1 without additional photosensitizer or sacrificial agent. The experimental and theoretical results revealed that the defective sites not only facilitated CO 2 adsorption but also promoted C–C coupling of *CO intermediates, thereby enhancing C 2 H 4 production. This work provides deep insights for designing advanced materials toward direct air‐to‐fuel conversion.
Regular hollow mesoporous superparticles with an opening window and controllable surface grooves can significantly improve the high-loading performance of aqueous zinc ion hybrid capacitors, but their synthesis remains a great challenge. Herein, an electrostatic force-assisted monomicelle confined assembly strategy is demonstrated for synthesizing such regular mesoporous hollow superparticles. The mesoporous superparticles feature a hollow (∼250 nm) in the center and a tailored transverse window (35–50 nm) to enable the superparticles to be totally connected from the inner to external surface, and a monolayer of spherical mesopores (∼15 nm) is arrayed in an orderly fashion on the hollow shell to form the unique crisscrossed grooves. Notably, an accurate manipulation in the width (29.5–62.4 nm), depth (2.1–40.7 nm), and number in the horizontal and vertical (11 × 11–5 × 5) grooves can be realized. Finally, the mesoporous superparticles as the high-loading electrodes in aqueous zinc ion hybrid capacitors exhibit a weak polarization, a high specific capacity (205 mAh g,–1 at 0.1 A g–1), and an excellent rate performance (105 mAh g–1 at 10 A g–1). The adjustability of surface grooves enables the orthogonal control of the charge transfer rate and ion diffusion rate. The mesoporous superstructures demonstrate the potential for energy storage applications in different environments.
Abstract Crystal‐facet heterojunction engineering of mesoporous nanoreactors with highly redox‐active represents an efficacious strategy for the transformation of CO 2 into valuable C 2 products (e.g., C 2 H 4 ). Herein, hollow mesoporous cube‐like CuS nanoreactors (~860 nm) with controlled anisotropic crystal‐facets are prepared through an interfacial‐confined ion dynamic migration‐rearrangement strategy. The regulation of the S 2− ion concentration facilitates the modulation of the highly active (110) to (100) crystal‐facet ratios from 0.119 to 0.288, and induces the formation of anisotropic crystal‐facet heterojunctions. The controllable crystal‐facet heterojunctions trigger the directional charge carrier migration, and are accompanied with the formation of tandem S‐defect sites (Cu 0 ‐S 1 @S 3 ). Both of them promote the efficient electron‐hole pair dissociation and attain asymmetric C−C coupling. The hollow mesoporous CuS nanoreactors with optimized crystal‐facet ratio of 0.224 (HMe‐CuS‐3) deliver a high selectivity of 72.7 % for the photocatalytic reduction of CO 2 to acetylene (C 2 H 2 ). Further constructed Au‐(110) and Co 3 O 4 ‐(100) spatially separated cascade nanoreactors (SS‐Au@Co 3 O 4 ‐CuS) achieve CO 2 ‐C 2 H 4 photoreduction, in which the Co‐sites enhance H 2 O dissociation to provide protons and the protonation of *CO to *COH. The *COH is further captured by Au‐sites to accomplish the asymmetric *CO‐*COH coupling and subsequent protonation, ensuring a high C 2 H 4 generation rate of 4.11 μmol/g/h with a selectivity as high as 90.6 %.
Stable, nonprecious catalysts are vital for large-scale alkaline water electrolysis. Here, we report a grafted superstructure, MOF@POM, formed by self-assembling a metal-organic framework (MOF) with polyoxometalate (POM). In situ electrochemical transformation converts MOF into active metal (oxy)hydroxides to produce a catalyst with a low overpotential of 178 millivolts at 10 milliamperes per square centimeter in alkaline electrolyte. An anion exchange membrane water electrolyzer incorporating this catalyst achieves 3 amperes per square centimeter at 1.78 volts at 80°C and stable operation at 2 amperes per square centimeter for 5140 hours at room temperature. In situ electrochemical spectroscopy and theoretical studies reveal that the synergistic interactions between metal atoms create a fast electron-transfer channel from catalytic iron and cobalt sites, nickel, and tungsten in the polyoxometalate to the electrode, stabilizing the metal sites and preventing dissolution.
A bimetallic MOF, CoMg-TCPP, is reported for the photocatalytic reduction of carbon dioxide to formic acid.
Read moreAbstract We explored a co‐dissolved strategy to embed mono‐dispersed Pt center into V 2 O 5 support via dissolving [PtV 9 O 28 ] 7− into [V 10 O 28 ] 6− aqueous solution. The uniform dispersion of [PtV 9 O 28 ] 7− in [V 10 O 28 ] 6− solution allows [PtV 9 O 28 ] 7− to be surrounded by [V 10 O 28 ] 6− clusters via a freeze‐drying process. The V centers in both [PtV 9 O 28 ] 7− and [V 10 O 28 ] 6− were converted into V 2 O 5 via a calcination process to stabilize Pt center. These double separations can effectively prevent the Pt center agglomeration during the high‐temperature conversion process, and achieve 100 % utilization of Pt in [PtV 9 O 28 ] 7− . The resulting Pt‐V 2 O 5 single‐atom‐site catalysts exhibit a CH 4 yield of 247.6 μmol g −1 h −1 , 25 times higher than that of Pt nanoparticle on the V 2 O 5 support, which was accompanied by the lactic acid photooxidation to form pyruvic acid. Systematical investigations on this unambiguous structure demonstrate an important role of Pt−O atomic pair synergy for highly efficient CO 2 photoreduction.
Read moreDue to complexities from the interaction between steel tube and concrete filling of concrete-filled steel tubular (CFST) columns, their strengths are very complicated, which is a highly nonlinear relation with material strengths and geometry. Categorical gradient Boosting (CatBoost), which is advanced boosting machine, is presented to solve the problems. A total of 3103 tests, which is divided in four datasets, is trained and tested the learners to determine the ultimate axial strength as the output variable while the strength of materials (concrete and steel) and geometry (e.g., diameters/width/heights, thickness, effective length, eccentricities) are the input ones. The comparison of the present results from 10-fold cross validation and those from the code predictions (AISC 360-16, Eurocode 4 and AS/NZS 2327) and previous study shows very high prediction accuracy in terms of coefficient of determination (R2), which is the lowest value (R2 = 0.964) for Dataset 2 and the highest one (R2 = 0.996) for Dataset 1. While the predictions from three codes beyond material limit and slenderness are less conservative than those within it, CatBoost provides nearly similar experiment results with the mean values as unity without any limits. This algorithm can be used to predict an accurate strength of CFST columns.
Read moreAbstract Although much effort has been devoted to improving photoelectrochemical water splitting of hematite (α-Fe 2 O 3 ) due to its high theoretical solar-to-hydrogen conversion efficiency of 15.5%, the low applied bias photon-to-current efficiency remains a huge challenge for practical applications. Herein, we introduce single platinum atom sites coordination with oxygen atom (Pt-O/Pt-O-Fe) sites into single crystalline α-Fe 2 O 3 nanoflakes photoanodes (SAs Pt:Fe 2 O 3 -Ov). The single-atom Pt doping of α-Fe 2 O 3 can induce few electron trapping sites, enhance carrier separation capability, and boost charge transfer lifetime in the bulk structure as well as improve charge carrier injection efficiency at the semiconductor/electrolyte interface. Further introduction of surface oxygen vacancies can suppress charge carrier recombination and promote surface reaction kinetics, especially at low potential. Accordingly, the optimum SAs Pt:Fe 2 O 3 -Ov photoanode exhibits the photoelectrochemical performance of 3.65 and 5.30 mA cm −2 at 1.23 and 1.5 V RHE , respectively, with an applied bias photon-to-current efficiency of 0.68% for the hematite-based photoanodes. This study opens an avenue for designing highly efficient atomic-level engineering on single crystalline semiconductors for feasible photoelectrochemical applications.
Read moreAbstract Recently, to achieve the goal of increasing both crop yield and water/nitrogen use efficiency with a better irrigation regime is a major challenge in semi-arid areas. In this study, we presented a two seasonal-field experiment that considers irrigation regimes, i.e., no irrigation (W0), irrigated in jointing (W1), both in jointing and flowering (W2) after the re-greening, and varieties (S086; J22) to compare the response of the sensitivity of wheat leaf physiological indicators, yield, water/N use efficiency and soil water consumption to irrigation regimes. The results showed that the WUE, IWUE and soil water-holding consumption (SWC) decreased with the increase in amount of irrigation. Additionally, 45.5% of the excessive irrigation water input did not promote wheat yield (W1 vs. W2). The degree of SWC in the 0–120 cm soil layer was highly related to wheat growth. S086 was beneficial for the usage of SWC under a low amount of irrigation. As well, irrigation positively affected the activities of superoxide dismutase (SOD) and catalase (CAT) in the flag leaf (P<0.05) during crop yield production. A decrease of irrigation helped to increase the concentrations of SS and Pro and decrease of amount of MDA for S086. Thus, a high yield of S086 was found under deficit irrigation (W1, a 31.3% reduction of irrigation water than that of W2). Thus, our studies suggested that one irrigation event in jointing stage for the S086 variety was essential to meet the win-win goal of high crop yield and water use efficiency with low groundwater consumption.
Read moreAbstract While the ambient N 2 reduction to ammonia (NH 3 ) using H 2 O as hydrogen source (2N 2 +6H 2 O=4NH 3 +3O 2 ) is known as a promising alternative to the Haber–Bosch process, the high bond energy of N≡N bond leads to the extremely low NH 3 yield. Herein, we report a highly efficient catalytic system for ammonia synthesis using the low‐temperature dielectric barrier discharge plasma to activate inert N 2 molecules into the excited nitrogen species, which can efficiently react with the confined and concentrated H 2 O molecules in porous metal–organic framework (MOF) reactors with V 3+ , Cr 3+ , Mn 3+ , Fe 3+ , Co 2+ , Ni 2+ and Cu 2+ ions. Specially, the Fe‐based catalyst MIL‐100(Fe) causes a superhigh NH 3 yield of 22.4 mmol g −1 h −1 . The investigation of catalytic performance and systematic characterizations of MIL‐100(Fe) during the plasma‐driven catalytic reaction unveils that the in situ generated defective Fe−O clusters are the highly active sites and NH 3 molecules indeed form inside the MIL‐100(Fe) reactor. The theoretical calculation reveals that the porous MOF catalysts have different adsorption capacity for nitrogen species on different catalytic metal sites, where the optimal MIL‐100(Fe) has the lowest energy barrier for the rate‐limiting *NNH formation step, significantly enhancing efficiency of nitrogen fixation.
Read moreABSTRACT This article is a response to the comment “Reassessing Machine Learning Techniques for Electrocatalyst Design: A Call for Robust Methodologies”. First, we clarify that the artificial neural network–SHapley Additive exPlanation (ANN–SHAP) method mentioned in the comment originates from the original work of Ding et al., which we only briefly summarized. In that study, nine different machine learning models were employed to predict the performance of proton exchange membrane fuel cells, among which the ANN model performed best. SHAP, together with multiple interpretability techniques (PDP, Tree‐based Rule, EIX, etc.), was used to cross‐validate feature importance, which was further compared with the results from manual feature selection, PCA, and t‐distributed stochastic neighbor embedding, and complemented by experimental validation to reduce the risk of bias amplification. We agree with the commenter that model interpretability should be approached with caution, as the absence of a definitive “ground truth” for feature importance remains a current challenge. However, benchmarking SHAP explanations against domain knowledge or validating them using synthetic datasets can help reduce the risk of misinterpretation. Regarding the unsupervised methods suggested in the comment (FA and HVGS), we consider them to have exploratory value for certain data structures, but caution is needed when applying them to experimental systems involving nonlinearity or high noise.
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