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The increasing amount of heavy metal copper ions (Cu2+) in industrial emissions, poses a serious threat to human health, biological environment, and resource scarcity. Capacitive deionization (CDI) is considered as a green and efficient method for desalination. It is crucial to develop high-performance electrodes for efficient operation of CDI that go beyond conventional carbon and yield considerable environmental benefits. Here, metal organic frameworks (MOFs) derived carbon-loaded cobalt metaphosphate (NC-Co(PO3)2) was prepared by lowtemperature gas-solid phosphating for Cu2+ removal as CDI electrode for the first time. NC-Co(PO3)2 demonstrated superior electrode structure and function due to the synergistic effects of electric double layer coupling PO bonds, the binding tendency of metaphosphate groups with Cu2+, and interfacial redox reactions induced by the labile valence state of cobalt. The optimal electrosorption capacity of NC-Co(PO3)2 was 95.41 mg g-1 at 1 V in 50 mL Cu2+ solution with splendid cyclic regeneration capability. Moreover, NC-Co(PO3)2 exhibited excellent selectivity and outstanding electrosorption performance in the presence of multiple coexisting ions and this CDI system realized the purification of actual copper-containing wastewater. A series of characterizations further revealed the specific mechanism of Cu2+ in adsorption-desorption process. Our finding strongly supported NCCo(PO3)2 electrode can extend the CDI platform's capability for effectively removing and retrieving Cu2+ from wastewater., Funding Agencies|National Natural Science Foundation of China [51778156]; Internal research project of Guangzhou University [YJ2023029]; Talent Cultivation Program of Guangzhou University [YJ2021005]; Guangdong Natural Science Foundation [2022A1515010441]; Basic Innovation Project for Graduate Students of Guangzhou University [2022GDJC-M43]

Due to a threat to human life from heavy metal ions pollution, unprecedented interest has been gained in the development of water purification technologies. Here, we explore another new approach to exploit a prospective carbon material for removing copper ions from aqueous solution based on rapid and easy capacitive deionization (CDI). Reasonable carbon materials modification with ideal composition and improved morphological structure is essential to additionally optimize the capabilities of CDI. We prepared a nitrogen-rich hierarchically porous carbon composites (CoFe-NC) with uniform cobalt (Co) and iron (Fe) doped metal in carbon skeleton by a simple impregnation and pyrolysis method, derived from zeolitic imidazolate framework-8, to use as highly effective CDI electrode for copper ions removal. The addition of Fe can facilitate the uniform dispersion of metals, and enable the formation of a stable carbon cage after pyrolysis. It can sufficiently expose active sites of the electrode materials and promote interfacial charge transfer, thus improving CDI electrosorption efficiency. CoFe-NC composites electrode can achieve outstanding deionization capacity (91.31 mg g-1) in 25 mg L-1 CuSO4 solu-tion. The carbon cage structure of CoFe-NC not only prevents aggregation of metals and avoids destruction of rich multistage pore system by pyrolysis, but also induces a faster ions transport rate. In addition, density functional theory calculations demonstrated that the co-doping of Co and Fe can remarkably increase the adsorption en-ergies of Cu2+ ions, leading to excellent selectivity, which indicates that CoFe-NC composites can be a desired CDI electrode material., Funding Agencies|National Natural Science Foundation of China [51778156]; Talent Cultivation Program of Guangzhou University [YJ2021005]; Guangdong Natural Science Foundation [2022A1515010441]; "Basic Innovation" Project for Graduate Students of Guangzhou University [2022GDJC-M43]

Cathode electrocatalyst is quite critical to realize the application of microbial fuel cells (MFCs). Perovskite oxides have been considered as potential MFCs cathode catalysts to replace Pt/C. Herein, Cu-doped perovskite oxide with a stable porous structure and excellent conductivity was successfully prepared through a sol-gel method. Due to the incorporation of Cu, CaFe0.9Cu0.1O3 has more micropores and a larger surface area, which are more conducive to contact with oxygen. Doping Cu resulted in more Fe3+ in B-site and thus enhanced its binding capability to oxygen molecules. The data from electrochemical test demonstrated that the as-prepared catalyst has good conductivity, high stability, and excellent ORR properties. Compared with Pt/C catalyst, CaFe0.9Cu0.1O3 exhibits a lower overpotential, which had an onset potential of 0.195 V and a half-wave potential of 0.224 V, respectively. CaFe0.9Cu0.1O3 displays an outstanding four-electron pathway for ORR mechanism and demonstrates superiors corrosion resistance and stability. The MFC with CaFe0.9Cu0.1O3 has a greater maximum power density (1090 mW m(-3)) rather than that of Pt/C cathode (970 mW m(-3)). This work demonstrated CaFe0.9Cu0.1O3 is an economic and efficient cathodic catalyst for MFCs., Funding Agencies|National Natural Science Foundation [51208122, 51778156, 51708142, 22076034]; Natural Science Foundation of Guangdong Province, China [2021A1515010067, 2022A1515010441]; Talent Cultivation Program of Guangzhou University [YJ2021005]

It is critical to develop non-noble metal (NNM) electrocatalysts with excellent stability and innovative activity for oxygen reduction reaction (ORR) in the microbial fuel cells (MFCs), which is a promising energy conversion technology. Herein, the preparation of iron carbide electrocatalysts (SrCO3/Fe3C) by the pyrolysis of a bimetal precursor (Sr and Fe) is proposed as a feasible strategy to realize a highly active electrocatalyst for ORR. Based on the catalytic potential of Sr-based materials, Fe species doping can provide more beneficial active sites for ORR. Concisely, the SrCO3/Fe3C(1:12) catalyst achieves the onset potential of 0.197 V (vs. Ag/AgCl) superior than Pt/C catalyst (0.193 V vs. Ag/AgCl) and the half-wave potential of -0.157 V (vs. Ag/AgCl) in 0.1-M KOH solution. Furthermore, the electrocatalyst exhibits nearly four-electron pathway, and generates less than 3% H2O2. Compared with Pt/C catalyst, it possesses preferable stability and superior methanol tolerance. Moreover, a composite electrode with SrCO3/Fe3C(1:12) as a catalyst on the carbon cloth demonstrated a superb air cathode in MFCs with a power density of 398.98 mW m(-2), which can outperform than 10 wt% Pt/C catalysts (342.13 mW m(-2)) on MFCs., Funding Agencies|National Natural Science FoundationNational Natural Science Foundation of China (NSFC) [51208122, 51778156, 51708142, 51708143]; Pearl River S&T Nova Program of Guangzhou [201806010191]; Science and Technology Program of Guangzhou [201707010256]; Guangzhou Universitys Training Program of Innovation Ability for Postgraduates [2020GDJC-M07]