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[Display omitted] • A new cationic imidazolium and porphyrin cross-linked POP was prepared by the bottom-up method. • The Imi-PPOPs-Br exhibited considerable Au (III) adsorption capacity (1543 mg g−1). • The mechanism was ascribed to the electrostatic interaction, strong binding and reduction. • The Imi-PPOPs-Br owns superior selectivity towards gold for the CPU leaching solution. • The Imi-PPOPs-Br possesses great recyclability and practical application potential. Developing ionic porous organic polymers (i-POPs) to retrieve gold from electronic waste is still in its infancy. Herein, for the first time, a cationic imidazolium and porphyrin cross-linked POPs, Imi-PPOPs-Br, was constructed by combining pyrrole and imidazolium-functionalized trialdehydes via the bottom-up method. As expected, the introduction of cationic imidazolium and porphyrin rings has endowed material high adsorption capacity (1543 mg/g), preferable reusability (more than eight times), and specific selectivity to Au (III). Multiple characterization results and density functional theory (DFT) calculations revealed that the adsorption mechanism of Au (III) by Imi-PPOPs-Br could be due to the electrostatic interaction between cationic Imi-PPOPs-Br and AuCl 4 − anions, strong bind of Au and N active sites, and reductive immobilization of Au (III) to Au (0). This study may put forward a new and facile strategy for constructing stable i-POPs that can be used as desirable absorbents in environmental fields. [ABSTRACT FROM AUTHOR]

[Display omitted] • Zero-valent iron with phosphate group-modified titanium dioxide was produced. • PTO-3nZVI and PTO-nZVI showed impressive adsorption properties for Cd(Ⅱ). • Pb(Ⅱ) and Cu(Ⅱ) had competitive effects for the removal of Cd(Ⅱ) on adsorbents. • Different zero-valent iron content of adsorbent showed different adsorption order. • XPS analysis and DFT calculation explain the adsorption behaviors together. In order to treat heavy metal pollutants in acid mine drainage, zero-valent iron/phosphoric titanium dioxide (PTO-3nZVI and PTO-nZVI) was developed with phosphoric acid treatment and loading of zero valent iron and showed excellent adsorption of heavy metals. PTO-3nZVI and PTO-nZVI greatly improved the adsorption capacity for the targeted heavy metal Cd(II) (308 mg·g−1 for PTO-3nZVI and 206 mg·g−1 for PTO-nZVI) through complexation and coprecipitation. Additionally, competitive adsorption occurred between Cd(II) and coexisting heavy metal ions (Pb(II) and Cu(II)), resulting in different adsorption effects for PTO-3nZVI and PTO-nZVI, and their adsorption efficiencies decreased in the order Cu(II) > Pb(II) > Cd(II) for PTO-3nZVI and Pb(II) > Cu(II) > Cd(II) for PTO-nZVI. Based on these two aspects, X-ray photoelectron spectrometer (XPS) analyses and Density Functional Theory (DFT) calculations were used to characterize the adsorption behaviors of PTO-3nZVI and PTO-nZVI. In particular, competitive relationships for different heavy metals were clearly revealed by binding energies, Frontier Molecular Orbitals (FMOs) analyses, electrostatic potentials, and total potential and differential charge analyses of adsorption sites, binding sites and binding strengths. [ABSTRACT FROM AUTHOR]

[Display omitted] • Cu/Fe–N–C exhibits exceptional chloramphenicol catalytic activity and stability. • Chloramphenicol is efficiently degraded by free radicals and non-free radicals. • The adsorption of persulfate on Fe/Cu–N is more favorable than that on Fe–N sites. • Adjacent atom-dispersed Cu–N optimizes the Fe 3d orbital bonding distribution. Advanced oxidation processes (AOPs) are promising ways for oxidative degradation of organic pollutants. Atom-dispersed transition metal–nitrogen–carbon (M–N–C) materials exhibit excellent efficiency in activating peroxide bonds and have been extensively pursued for environmental remediation. However, M–N–C with single atoms suffer from intrinsic performance limit of complicated catalytic reactions due to structural simplicity and lack of synergistic active sites. Herein, derived from Fe/Cu–coordinated zeolitic imidazolate frameworks with molecular-scale cages, a well–designed catalyst featuring Fe–Cu dual–metal sites coordinated with N–doped carbon (Fe/Cu–N–C) was fabricated. Compared to the single-atom iron catalyst (Fe–N–C), Fe/Cu–N–C significantly enhanced the chloramphenicol removal rate from 0.073 to 0.093 min−1 due to the synergistic effects of Fe–Cu dual active site. Furthermore, Fe/Cu–N–C exhibits fantastic reactivity for peroxydisulfate (PDS) activation in a wide pH range (3.1 – 10.3). Density functional theory calculations revealed that Fe/Cu–N is the major active site, where electrons transfer from Cu to Fe ensure the low-valence state of Fe for catalytic oxidation. Besides, the optimization of adjacent Cu–N sites improves the bonding orbital distribution of Fe 3d orbitals and promotes the adsorption and cracking of PDS. These findings reveal the cooperative mechanism of Fe–Cu dual–atom site on PDS activation and develop a promising platform toward environmental purification. [ABSTRACT FROM AUTHOR]

DFT calculation is used to study the electrochemical capacity enhancement mechanism of the fabricated flexible 3D porous rOHNM-AGs electrodes based on open-hollow Ni-MOF microspheres with high mechanical strength and superior electrochemical properties. [Display omitted] • 3D rOHNM-AGs are achieved by embedding open-hollow Ni-MOF microspheres into graphene nanosheets. • DFT calculation reveals charge-transfer interaction between the rOHNM-AGs and OH– ions. • The rOHNM-AGs/KOH/PVA film can be twisted with different angles, which can lift 500 g plastic bottle. • The fabricated rOHNM-AGs electrode exhibit superb specific capacitance of 1644F·g−1 at 1 A·g−1. • A portable multifunctional instrument can be powered by all-solid-state supercapacitor device for 15 mins. Metal-organic frameworks (MOFs) are extensively used for electrode materials of supercapacitors under their unique characteristics like customizable pore size, plentiful active sites and tunable structure. However, the MOFs lack adequate electrical conductivity and satisfactory stability, when directly applied to supercapacitor electrode materials, limiting the further improvement of their electrochemical properties. Accordingly, three-dimensional porous aerogels (rOHNM-AGs) have been achieved by embedding open-hollow nickel-based metal–organic framework microspheres between graphene layers. Under the controllable and highly ordered metal nodes as well as organic linkers, the prepared rOHNM-AGs still reserve the preponderance of MOF materials with multifarious exceptional constituent and configurational benefits. Furthermore, the remarkable electrical conductivity from graphene leads to a significant increase in electron/ion transport rate. In addition, charge-transfer interaction between the acceptor of OH– ions and the donor of rOHNM-AGs has been exposed by the density functional theory calculations. Moreover, a pliable and high tensile rOHNM-AGs/PVA/KOH film electrode has been fabricated by the PVA/KOH gel-electrolyte, which is capable of curving at multifarious angles. For actual utilizations, the manufactured supercapacitor apparatus can run a multi-purpose display for over 15 mins. Therefore, this groundbreaking research furnishes a new inspiration for preparing composite electrodes based on MOFs and graphene for flexible asymmetric supercapacitors. [ABSTRACT FROM AUTHOR]

• SbBi x nanoparticles embedded in ultra-thin carbon networks are designed. • SbBi x @C exhibits excellent performance in both sodium and potassium storage. • The influence of proportion in SbBi x on energy storage behavior is revealed. • SEI composition and particle surface states play an important role in energy storage. The alloy proportions of SbBi x show obvious influence on sodium/potassium storage. Herein, SbBi x nanoparticles embedded in ultra-thin carbon networks (SbBi x @C, x = 1, 0.5, 0.15) are successfully synthesized by a facile salt template assisted pyrolysis method. The effect of different alloy proportions on the chemical and electrochemical properties of active materials is revealed. Density functional theory calculation demonstrates that SbBi 0.5 has the smallest formation energy (−5.131 eV) and the smallest volume expansion rate for both sodium/potassium storage (222%/376%). Benefiting from the optimized volume expansion for both sodium/potassium storage and carbon networks structure, the optimized SbBi 0.5 @C anode shows high reversible capacities of 301 mAh/g and 390 mAh/g after 100 cycles at 0.1 A/g for sodium/potassium storage, respectively. It is also observed that the SbBi 0.5 @C anode delivers different behaviours of sodium/potassium storage, which is due to the various composition of SEI films formed after sodium/potassium storage. It is believed that this work provides a synthetic strategy for fabricating alloy-type anode materials for SIBs/PIBs, in view of structure design and the regulation of alloy proportion. [ABSTRACT FROM AUTHOR]

• CQDs provided bi-function in domination of (0 0 1) facets and formation of OVs. • Exposed facets of (0 0 1) and formation of OVs was investigate by DFT calculation. • The simultaneous photocatalytic mechanism of TCH and Cr (VI) was discussed. • CQDs/BiOBr oxidized high-toxic pollutant to less-toxic products. Crystal facet engineering and defect engineering are promising strategies to enhance the photocatalytic performance of BiOBr, but limited work has been reported to realize the simultaneous exposure of highly active facets and the introduction of oxygen vacancies by a single approach. In this work, carbon quantum dots-modified bismuth oxybromide (CQDs/BiOBr) with {0 0 1} exposed facets and surface oxygen vacancies was synthesized by a two-step hydrothermal method. The characterization and density functional theory calculation results verified that the introduction of CQDs promoted the growth of BiOBr with highly exposed {0 0 1} crystal facets and induced the in situ formation of oxygen vacancies by extracting O atoms from the [Bi 2 O 2 ]2+ layer. The dual functionality of the CQDs allowed them to simultaneously remove tetracycline hydrochloride (TCH) and Cr(VI) under visible light irradiation. The photocatalytic reaction rate constants in the coexisting pollutant system were 3.71 (TCH) and 13.6-times (Cr(VI)) higher than those of the mono-pollutant systems. This work provides a candidate method to design highly efficient catalysts for environmental remediation. [ABSTRACT FROM AUTHOR]

A facile in situ self-catalysis and subsequent chemical transformation route were developed to encapsulated ultrafine FeSe 2 nanoparticles into bamboo-like 3D N-doped carbon nanotubes networks. Realizing excellent lithium and sodium ion storage performances. The Li+/Na+ storage mechanisms were investigated via in situ characterization tests and density functional theory (DFT) calculations. [Display omitted] • A facile in situ self-catalysis and subsequent chemical transformation route has been explored to FeSe 2 @CNTs composite. • The ultrafine FeSe 2 nanoparticles were encapsulated within the bamboo-like N-doped carbon nanotubes. • The in situ electroanalytical techniques and DFT calculations reveal the energy storage mechanism. • The FeSe 2 @CNTs composite exhibits ultratable cycling performance and ultrahigh rate capability. Encapsulating the multifunctional nanostructures within a lightweight nanocarbon network is considered to be a promising strategy for developing state-of-the-art electrodes for alkali metal-ion batteries (AMIBs). Herein, the ultrafine FeSe 2 nanoparticles (NPs) were encapsulated within the bamboo-like N-doped carbon nanotubes (FeSe 2 @CNTs) via a rationally in situ self-catalysis and subsequent chemical transformation, realizing a workable capacity and stable architecture. The 3D interactive CNT network provides a fast electron/ion conducting path, and constructs a solid electronic link between the CNTs and FeSe 2 NPs. The ultrafine dimension of FeSe 2 NPs ensures small volume change and short Li+/Na+ diffusion distance during charge and discharge. Profiting from the fast transport capability of both electrons and ions, the unique FeSe 2 @CNTs exhibits outstanding host potential for Li+ storage with a capability of 397 mA h g−1 at 10 A g−1. Serving as anode for Na+ storage, the optimized electrode possesses excellent rate capability of 329 mA h g−1 at 8 A g−1. Additionally, the Li+/Na+ storage mechanisms are further revealed by in situ electrochemical techniques and density functional theory (DFT) calculations. The present work inspired a new window for developing high-performance hybrids towards various electrochemical energy applications. [ABSTRACT FROM AUTHOR]