Kochia sieversiana (Pall.) C. A. M., a naturally alkali-resistant halophyte, was chosen as the test organism for our research. The seedlings of K. sieversiana were treated with varying (0-400 mM) salt stress (1:1 molar ratio of NaCl to Na 2 SO 4 ) and alkali stress (1:1 molar ratio of NaHCO 3 to Na 2 CO 3 ). The concentrations of various solutes in fresh shoots, including Na + , K + , Ca 2+ , Mg 2+ , Cl À , SO 4 2À , NO 3 À , H 2 PO 3 À , betaine, proline, soluble sugar (SS), and organic acid (OA), were determined. The water content (WC) of the shoots was calculated and the OA components were analyzed. Finally, the osmotic adjustment and ion balance traits in the shoots of K. sieversiana were explored. The results showed that the WC of K. sieversiana remained higher than 6 [g g À1 Dry weight (DW)] even under the highest salt or alkali stress. At salinity levels >240 mM, proline concentrations increased dramatically, with rising salinity. We proposed that this was not a simple response to osmotic stress. The concentrations of Na + and K + all increased with increasing salinity, which implies that there was no competitive inhibition for absorption of either in K. sieversiana. Based on our results, the osmotic adjustment feature of salt stress was similar to that of alkali stress in the shoots of K. sieversiana. The shared essential features were that the shoots maintained a state of high WC, OA, Na + , K + and other inorganic ions, accumulated largely in the vacuoles, and betaine, accumulated in cytoplasm.On the other hand, the ionic balance mechanisms under both stresses were different. Under salt stress, K. sieversiana accumulated OA and inorganic ions to maintain the intracellular ionic equilibrium, with close to equal contributions of OA and inorganic ions to anion. However, under alkali stress, OA was the dominant factor in maintaining ionic equilibrium. The contribution of OA to anion was as high as 84.2%, and the contribution of inorganic anions to anion was only 15.8%. We found that the physiological responses of K. sieversiana to salt and alkali stresses were unique, and that mechanisms existed in it that were different from other naturally alkaliresistant gramineous plants, such as Aneurolepidium chinense, Puccinellia tenuiflora.

Because they provide lower cost but comparable activity to precious platinum (Pt)-based catalysts, nonprecious iron (Fe)-based materials, such as Fe/FeC and Fe-N-C, have gained considerable attention as electrocatalysts for the oxygen reduction reaction (ORR). However, their practical application is hindered by their poor stability, which is attributed to the defective protection of extremely unstable Fe nanoparticles. Here, we introduce a synthesis strategy for a stable Fe-based electrocatalyst, which was realized by defect-free encapsulation of Fe nanoparticles using a two-dimensional (2D) phenazine-based fused aromatic porous organic network (Aza-PON). The resulting Fe@Aza-PON catalyst showed electrocatalytic activity (half-wave potential, 0.839 V; Tafel slope, 60 mV decade) comparable to commercial Pt on activated carbon (Pt/C, 0.826 V and 90 mV decade). More importantly, the Fe@Aza-PON displayed outstanding stability (zero current loss even after 100 000 cycles) and tolerance against contamination (methanol and CO poisoning). In a hybrid Li-air battery test, the Fe@Aza-PON demonstrated performance superior to Pt/C.

Closing both the carbon and nitrogen loops is a critical venture to support the establishment of the circular, net‐zero carbon economy. Although single atom catalysts (SACs) have gained interest for the electrochemical reduction reactions of both carbon dioxide (CO2RR) and nitrate (NO3RR), the structure–activity relationship for Cu SAC coordination for these reactions remains unclear and should be explored such that a fundamental understanding is developed. To this end, the role of the Cu coordination structure is investigated in dictating the activity and selectivity for the CO2RR and NO3RR. In agreement with the density functional theory calculations, it is revealed that Cu‐N4 sites exhibit higher intrinsic activity toward the CO2RR, whilst both Cu‐N4 and Cu‐N4−x‐Cx sites are active toward the NO3RR. Leveraging these findings, CO2RR and NO3RR are coupled for the formation of urea on Cu SACs, revealing the importance of *COOH binding as a critical parameter determining the catalytic activity for urea production. To the best of the authors’ knowledge, this is the first report employing SACs for electrochemical urea synthesis from CO2RR and NO3RR, which achieves a Faradaic efficiency of 28% for urea production with a current density of −27 mA cm–2 at −0.9 V versus the reversible hydrogen electrode.

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Developing cost-effective, efficient bifunctional electrocatalysts for the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) is the heart of metal−air batteries as a renewable-energy technology. Herein, welldistributed nanopolyhedron (NP) Co 3 O 4 grown on iron (Fe) encapsulated in graphitic layers on a nitrogenated, porous two-dimensional (2D) structure, namely, a C 2 N matrix, (NP Co 3 O 4 /Fe@C 2 N), presents an outstanding bifunctional catalytic activity with a comparable overpotential and Tafel slope to those of benchmark Pt/C and IrO 2 . The rationally designed atomic configuration of Co 3 O 4 on the C 2 N matrix has a well-controlled NP morphology with a (111) plane, leading to bifunctional activities for the ORR and OER. Interestingly, the specific interaction between the NP Co 3 O 4 nanoparticles and the C 2 N matrix introduces synergistic coupling and changes the electronic configuration of Co atoms and the C 2 N framework. Benefiting from the synergistic coupling of Co 3 O 4 with the C 2 N matrix, the NP Co 3 O 4 /Fe@C 2 N electrocatalyst exhibits exceptionally high stability and an even lower charge−discharge overpotential gap of 0.85 V at 15 mA cm −2 than that of the Pt/C+IrO 2 catalyst (1.01 V) in Zn−air batteries. This work provides insights into the rational design of a metal oxide on a C 2 N matrix for bifunctional, low-cost electrochemical catalysts.

SummaryCarbon capture, utilization, and sequestration technologies have been extensively studied to utilize carbon dioxide (CO2), a greenhouse gas, as a resource. So far, however, effective technologies have not been proposed owing to the low efficiency conversion rate and high energy requirements. Here, we present a hybrid Na-CO2 cell that can continuously produce electrical energy and hydrogen through efficient CO2 conversion with stable operation for over 1,000 hr from spontaneous CO2 dissolution in aqueous solution. In addition, this system has the advantage of not regenerating CO2 during charging process, unlike aprotic metal-CO2 cells. This system could serve as a novel CO2 utilization technology and high-value-added electrical energy and hydrogen production device.

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An activated carbon nanofiber (CNF) is prepared with incorporated Fe‐N‐doped graphene nanoplatelets (Fe@NGnPs), via a novel and simple synthesis approach. The activated CNF–Fe@NGnP catalysts exhibit substantially improved activity for the oxygen reduction reaction compared to those of commercial carbon blacks and Pt/carbon catalysts.