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Drought is one of major environmental determinants of plant growth and productivity. Alfalfa (Medicago sativa) is a legume perennial forage crop native to the arid and semi-arid environment, which is an ideal candidate to study the biochemical and molecular mechanisms conferring drought resistance in plants. In this study, drought stress responses of two alfalfa varieties, Longdong and Algonquin, were comparatively assayed at the physiological, morphological, and transcriptional levels. Under control condition, the drought-tolerant Longdong with smaller leaf size and lower stomata density showed less water loss than the drought-sensitive Algonquin. After exposing to drought stress, Longdong showed less severe cell membrane damage, more proline, and ascorbate (ASC) contents and less accumulation of H2O2 than Algonquin. Moreover, significantly higher antioxidant enzymes activities after drought treatment were found in Longdong when compared with Algonquin. In addition, transcriptional expression analysis showed that Longdong exhibited significantly higher transcripts of drought-responsive genes in leaf and root under drought stress condition. Taken together, these results indicated that Longdong variety was more drought-tolerant than Algonquin variety as evidenced by less leaf firing, more lateral root number, higher relative aboveground/underground biomass per plant and survival rate.

Electrocatalytic CO2 reduction reaction (CO2RR) can store and transform the intermittent renewable energy in the form of chemical energy for industrial production of chemicals and fuels, which can dramatically reduce CO2 emission and contribute to carbon-neutral cycle. Efficient electrocatalytic reduction of chemically inert CO2 is challenging from thermodynamic and kinetic points of view. Therefore, low-cost, highly efficient, and readily available electrocatalysts have been the focus for promoting the conversion of CO2. Very recently, interface engineering has been considered as a highly effective strategy to modulate the electrocatalytic performance through electronic and/or structural modulation, regulations of electron/proton/mass/intermediates, and the control of local reactant concentration, thereby achieving desirable reaction pathway, inhibiting competing hydrogen generation, breaking binding-energy scaling relations of intermediates, and promoting CO2 mass transfer. In this review, we aim to provide a comprehensive overview of current developments in interface engineering for CO2RR from both a theoretical and experimental standpoint, involving interfaces between metal and metal, metal and metal oxide, metal and nonmetal, metal oxide and metal oxide, organic molecules and inorganic materials, electrode and electrolyte, molecular catalysts and electrode, etc. Finally, the opportunities and challenges of interface engineering for CO2RR are proposed.

Electrochemical CO2 reduction (ECR) to value‐added chemicals and fuels is regarded as an effective strategy to mitigate climate change caused by CO2 from excess consumption of fossil fuels. To achieve CO2 conversion with high faradaic efficiency, low overpotential, and excellent product selectivity, rational design and synthesis of efficient electrocatalysts is of significant importance, which dominates the development of ECR field. Individual organic molecules or inorganic catalysts have encountered a bottleneck in performance improvement owing to their intrinsic shortcomings. Very recently, organic–inorganic hybrid nanomaterials as electrocatalysts have exhibited high performance and interesting reaction processes for ECR due to the integration of the advantages of both heterogeneous and homogeneous catalytic processes, attracting widespread interest. In this work, the recent advances in designing various organic–inorganic hybrid nanomaterials at the atomic and molecular level for ECR are systematically summarized. Particularly, the reaction mechanism and structure–performance relationship of organic–inorganic hybrid nanomaterials toward ECR are discussed in detail. Finally, the challenges and opportunities toward controlled synthesis of advanced electrocatalysts are proposed for paving the development of the ECR field.

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The catalytic conversion of carbon dioxide (CO 2 ) into high value-added chemicals is of great significance to address the pressing carbon cycle issues. Reticular chemistry of metal-organic frameworks (MOFs)-based materials exhibits great potential and effectiveness to face CO 2 challenge from capture to conversion. To date, the integrated nanocomposites of nanostructure and MOF have emerged as a powerful heterogeneous catalysts featured with multifold advantages including synergistic effects between the two interfaces, confinement effect of meso-and micropores, tandem reaction triggered by multiple active sites, high stability and dispersion, and so on. Given burgeoning carbon cycle and nanostructure@MOFs, this review highlights some of important advancements to provide a full understanding on the synthesis and design of nanostructure@MOFs composites to facilitate carbon cycle through CO 2 photocatalytic, electrocatalytic, and thermal conversion. Afterward, the catalytic applications of some representative nanostructure@MOFs composites are categorized, in which the origin of activity or structure-activity relationship is summarized. Finally, the opportunities and challenges are proposed for inspiring the future development of nanostructure@MOFs composites for carbon cycle.

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