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When copper ores containing pyrite are crushed and ground, many unavoidable Fe3+ ions will be produced and enter the flotation process. At present, the adsorption mechanism of Fe3+ on chalcopyrite and pyrite surfaces is not clear. Here, the adsorption behaviors of Fe3+ on the surfaces of chalcopyrite and pyrite were systematically investigated by micro-flotation tests, infrared spectra studies, X-ray photoelectron spectroscopy analysis (XPS), first-principles density functional theory calculations and theoretical analysis of the coordination field. The micro-flotation tests showed that the recovery rate of pyrite reduced with the growth of pH, but the recovery rate of chalcopyrite was basically unchanged. The infrared spectra analysis revealed that the intensities of the characteristic xanthate peaks of the C=S and C-O-C groups in the Fe3+-treated pyrite surface changed more noticeably than those of the xanthate peaks of the Fe3+-treated chalcopyrite. XPS showed that Fe (OH)3 was more easily and spontaneously adsorbed on pyrite than chalcopyrite surfaces. First-principles DFT calculations and electronic structure analysis further showed that pyrite had a stronger adsorption of Fe (OH)3 than chalcopyrite. This work sheds new light on the adsorption mechanism of Fe3+ on the surfaces of chalcopyrite and pyrite during flotation. [ABSTRACT FROM AUTHOR]

Conjugated coordination polymers (CCPs) with extended π–d conjugation, which can effectively promote long‐range delocalization of electrons and enhance conductivity, are superior to traditional metal‐organic frameworks (MOFs) and attracted great attention for potential applications in chemical sensors, electronics, energy conversion/storage devices, etc. However, the precise construction of CCPs is still challenging due to the complex and uncontrollable reactions of CCPs. Herein, two different framework dimensions of CCPs are controllably realized by employing the same ligand (2,3,5,6‐tetraaminobenzoquinone (TABQ)) and the same metal (copper) as center ions. The manipulation of reaction leads to different valences of ligands and metal ions, different coordination geometries, and thereby 1D‐CuTABQ and 2D‐CuTABQ frameworks, respectively. High performance of charge storage is hence achieved involving the storage of both cations and anions, and therein, 2D‐CuTABQ shows a high reversible capacity of ≈305 mAh g−1, good rate capability and high capacity retention (≈170 mAh g−1 after 2000 cycles at 5 A g−1 with 0.01% decay per cycle), which outperforms 1D‐CuTABQ and almost all of the reported MOFs as cathodes for batteries. These results highlight the delicate structural control of CCPs for high‐performance batteries and other various applications. [ABSTRACT FROM AUTHOR]

The oxidation of π–d‐conjugated coordination polymers (CCPs) accompanied with anion insertion has the merits of increasing the capacity and elevating the discharge voltages. However, previous reports on this mechanism either required more investigations or showed low capacity and poor cyclablity. Herein, triphenylene‐catecholate‐based two‐dimensional CCPs are constructed by employing inactive transition‐metal ions (Zn2+) as nodes, forming Zn‐HHTP. Substantial characterizations and theoretical calculations indicate the successive storage of cations and anions by redox reactions of only ligands, leading to a high reversible capacity of ≈150 mAh g−1 at 100 mA g−1 and a remarkable capacity retention of 90 % after 1000 cycles. On the contrary, as a control experiment, the analogous CCPs (Cu‐HHTP) with Cu2+ nodes, where both ligands and metal ions undergo redox reactions, accompanied by the storage of only Na+ cations, show a much poorer cyclability. These results highlight the importance of redox reactions of only ligands for long‐term cycle life and the insight into the storage mechanisms deepens our understanding on CCPs for the further design of CCPs with high performance. [ABSTRACT FROM AUTHOR]