Qing Yuan

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.

Green hydrogen energy from electrocatalytic hydrogen evolution reactions (HERs) has gained much attention for its advantages of low carbon, high efficiency, interconnected energy medium, safety, and controllability. Non-precious metals have emerged as a research hotspot for replacing precious metal catalysts due to low cost and abundant reserves. However, maintaining the stability of non-precious metals under harsh conditions (e.g., strongly acidic, alkaline environments) remains a significant challenge. By leveraging the curling properties of two-dimensional materials, a new class of catalysts, encapsulating transition metal nanoparticles inside carbon (TM@C) chainmail, has been successfully developed. This catalyst can effectively isolate the active metal from direct contact with harsh reaction media, thereby delaying catalyst deactivation. Furthermore, the electronic structure of the carbon layer can be regulated through the transfer of electrons, which stimulates its catalytic activity. This addresses the issue of the insufficient stability of traditional non-precious metal catalysts. This review commences with a synopsis of the synthetic advancement of the engineering of TM@C chainmail catalysts. Thereafter, a critical discussion ensues regarding the electrocatalytic performance of TM@C chainmail catalysts during hydrogen production. Ultimately, a comprehensive review of the conformational relationship between the structure of TM@C chainmail catalysts and HER activity is provided, offering substantial support for the large-scale application of hydrogen energy.

The insight of the activity phase and reaction mechanism is vital for developing high-performance ammonia synthesis electrocatalysts. In this study, the origin of the electronic-dependent activity for the model Cu₂O catalyst toward ammonia electrosynthesis with nitrate was probed. The modulation of the electronic state and oxygen vacancy content of Cu₂O was realized by doping with halogen elements (Cl, Br, I). The electrocatalytic experiments showed that the activity of the ammonia production depends strongly on the electronic states in Cu₂O. With increased electronic state defects in Cu₂O, the ammonia synthesis performance increased first and then decreased. The Cu₂O/Br with electronic defects in the middle showed the highest ammonia yield of 11.4 g h⁻¹ g⁻¹ at −1.0 V (vs. RHE), indicating that the pattern of change in optimal ammonia activity is consistent with the phenomenon of volcano curves in reaction chemistry. This work highlights a promising route for designing NO₃⁻RR to NH₃ catalysts.

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.

Thermal stimulation methods of hydrate exploitation with chemical self-heating solution began to be investigated in the recent years. However, the exothermic characteristics of chemical self-heating solution during the gas hydrate exploitation process was not investigated systematically now. In this work, the effects of reagent concentration, acid variety, acid concentration on the exothermic characteristics were investigated by a self-designed high pressure autoclave with a 11.75 L volume, whose diameter and length is 100 and 1,500 mm, respectively. The experimental results showed that the temperature of hydrate reservoir will change in a wide range (from 100°C to −3°C) during the injection process of self-heating solution which was a large challenge to control the rate of heat release. During the self-heating solution injection, the temperature decreased quickly because of the strong endothermic reaction of hydrate dissociation promoted by the salt effect of self-heating solution, and then the temperature increased quickly because of exothermic reaction of self-heating solution. The exothermic rate of self-heating solution increased with the increase of reagent concentration, the acid concentration and the acidity. In all of the experiments, the temperatures near the inlet entrance were much higher than that in the deeper area, which illustrated that the effective heating area is the areas near the entrance. In the end, the different injection mode of mixed injection and sectional injection was also investigated, and it was found that the temperature peak in the near area with mixed injection mode is higher than that with sectional injection mode, however, the exothermic performance with sectional injection mode is better than that with mixed injection in the area far away from the inlet entrance. The exothermic characteristics studies of self-heating solution in this work can lay the necessary foundation of the further studies of self-heating solution in the exploitation of natural gas hydrate.

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.