Three soluble conjugated polymers, named BEDPP, FLDPP, and CADPP, were prepared through the Suzuki polymerized reaction, and employed benzene (BE), fluorene (FL), and carbazole (CA) as the donor units, respectively. The electron-deficient molecule 2,5-bis-(2-octyldodecyl)-3,6-bis-(5-bromo-thiophene)-pyrrole[3-c]pyrrole-1,4-diketone(DPP) was introduced and used as the acceptor unit. The properties of these three copolymers were studied by a series of detailed characterization analysis, including X-ray photoelectron spectroscopy (XPS), colorimetry, electrochemical measurements, spectroelectrochemistry, kinetics, quantitative calculation, and thermogravimetric (TG) analysis, etc. The results revealed that BEDPP displayed a blue color in the neutral state and a light brown color in the oxidized state, FLDPP exhibited a cyan color in the neutral state and a gray color in the oxidized state, while CADPP displayed pure blue color in the neutral state and a light gray color in the oxidized state. All these polymers possess narrow optical band gaps lower than 1.80 eV and satisfactory thermal stability. The kinetic characterization showed that the optical contrasts (ΔT%) in the near-infrared region were superior to the visible region. The optical contrasts of BEDPP, FLDPP, and CADPP are 41.32%, 42.39%, and 45.95% in the near-infrared region, respectively, which made them a good application prospect in the near-infrared region. Amid the three polymers, CADPP has the highest coloration efficiency (around about 288 cm²·C⁻¹) and fast switching times (0.77 s in the coloring process and 0.52 s in the bleaching process) in the visible region, and the comprehensive performance of CADPP can be comparable to that of the reported D-A (Donor-Acceptor) type blue color polymers. In general, based on the good performances and the stable neutral blue color, the three polymers had profound theoretical significance for the development of electrochromic material and the completion of the RGB (Red, Green, Blue) color space.

In this work, we prepared a green, cheap material by chelating humic acid with ferric ions (HA-Fe) and used it as an anode material in LIBs for the first time. From the SEM, TEM, XPS, XRD, and nitrogen adsorption–desorption experimental results, it was found that the ferric ion can chelate with humic acid successfully under mild conditions and can increase the surface area of materials. Taking advantage of the chelation between the ferric ions and HA, the capacity of HA-Fe is 586 mAh·g⁻¹ at 0.1 A·g⁻¹ after 1000 cycles. Moreover, benefitting from the chelation effect, the activation degree of HA-Fe (about 8 times) is seriously improved compared with pure HA material (about 2 times) during the change–discharge process. The capacity retention ratio of HA-Fe is 55.63% when the current density increased from 0.05 A·g⁻¹ to 1 A·g⁻¹, which is higher than that of HA (32.55%) and Fe (24.85%). In the end, the storage mechanism of HA-Fe was investigated with ex-situ XPS measurements, and it was found that the C=O and C=C bonds are the activation sites for storage Li ions but have different redox voltages.

Sustainable recovery of lithium from salt lake brines is essential for the transition toward clean energy but remains challenged by low Li ⁺ concentrations and high Mg ²⁺ interference. Herein, we develop a heterostructure‐engineered ternary composite, conductive metal‐organic frameworks (c‐MOFs) coupled with a MoSe ₂ @MXene framework for efficient and selective lithium extraction by capacitive deionization (CDI) technology. The c‐MOFs Fe‐ tetrahydroxybenzoquinone (Fe‐THBQ) provide abundant redox‐active sites for Li⁺ capture, while the MoSe ₂ @MXene framework accelerates ion transport rate and provides structural robustness. X‐ray absorption spectroscopy (XAS) confirms that strong interfacial Fe─Se coordination bonds establish a continuous Fe‐Se‐Mo charge‐transfer pathway for enhanced conductivity and ion selectivity. Thus, the Fe‐THBQ@MoSe ₂ @MXene electrode delivers exceptional Li⁺ capture capacity (4.05 mmol g ⁻¹ ), ultrafast adsorption rate (0.98 mmol g ⁻¹ min ⁻¹ ), superior cycling stability (91.3% retention after 50 cycles), and remarkable Li⁺ selectivity with high Mg/Li ratios in both model solutions and real Dachaidan salt lake brine. Ex situ X‐ray diffraction analyses reveal a dual Li ⁺ storage mechanism involving Fe ²⁺ /Fe ³⁺ redox activity and reversible interlayer intercalation. Importantly, density functional theory (DFT) calculations confirm a substantially lower migration barrier for Li⁺ (0.052 eV) compared to competing cations, underpinning the observed selectivity. This work highlights a rational heterostructure design strategy for advancing CDI technology in lithium recovery.