Hollow Porous Structure Research Articles

Metal Organic Framework‐Derived Anionic P‐Substitution toward CoNiSe‐P with Excellent Electrochemical Stability for Supercapacitor

AbstractThe regulation of nanostructures and composition can significantly enhance the electrochemical activity and accelerate electrochemical reaction kinetics of electrode material. Herein, metal organic framework(MOF) is used as self‐sacrificing templates to prepare CoNiSe‐P by hydrothermal with following selenylation and phosphorization treatment. Due to the hollow porous structure, rich electrochemical active sites and elements synergistic influence, the obtained CoNiSe‐P electrode shows a high capacity of 838 C g−1, which is much higher than CoNiSe (322 C g−1) and CoNiP (616 C g−1). Furthermore, CoNiSe‐P electrode shows excellent rate characteristic (685 C g−1 at 20 A g−1) and ultrahigh electrochemical stability with capacity retention of 99.6% after 10 000 cycles. More importantly, an asymmetric supercapacitor is assembled with CoNiSe‐P as the positive electrode and nitrogen‐doped porous carbon as the negative electrode delivers an energy density of 42.4 Wh kg−1 at 266.6 W kg−1 and maintains a specific capacitance of 96.8% after 10 000 cycles. Significantly, the asymmetric supercapacitor shows a high energy density up to 21.3 Wh kg−1 at a very high power density of 21.3 kW kg−1, higher than those of previously reported asymmetric supercapacitors.

Stress-relieved hollow porous carbon nanoring structures anchored with ZnCo2O4 nanoparticles towards super stable lithium storage

Stress-induced structural mechanical instability is a common occurrence in the electrode material during electrochemical cycling, especially for composite material systems. The structural mechanics engineering of nanocomposites comprising electrochemical active materials and carbon with novel structures holds great promise in addressing this issue. However, conventional carbonaceous materials often encounter challenges in long-term durability and high specific capacity stemming from their intrinsic uneven stress distribution and few active sites. Herein, finite element analysis reveals that the ring-like structure effectively mitigates stress concentration from expansion and possesses high packing density, outperforming traditional nanosphere and nanocube architectures. Accordingly, nanocomposites consisting of hollow porous nanostructured N-doped carbon nanorings (N-CNRs) anchored with bimetallic ZnCo2O4 nanoparticles are designed, which exhibit an extraordinary cycling performance for lithium storage with 96.4 % capacity retention following 1000 cycles and an impressively low storage degradation rate of 0.00357 % per cycle, as well as displaying an excellent specific capacity (1218 mA h/g at 0.1 A g−1) and outstanding rate performance (565 mA h/g at 5.0 A g−1). The well-engineered design nanocomposite features the synergistic effect of electrochemically active ZnCo2O4 nanoparticles integrated with structurally stable carbon nanorings for enhanced electrochemical performance.

MOF-derived metal oxides with hollow porous nanocube structure realize ultra-wideband, lightweight, and anticorrosion microwave absorber

High density, skin effect, and environmental instability are significant limitations that restrict the application of metal-based microwave absorbers in achieving lightweight, high performance, and long service life. This study broke from traditional methods for preparing a microwave absorber Mn2O3-Fe3O4@PPy (polypyrrole) by employing an innovative annealing process to convert metal into metal oxide by the introduction of metal organic framework (MOF), which effectively achieving a more lightweight absorber material with hollow porous nanocube structure. Subsequently, PPy was coated onto the metal oxide surface to form a core-shell structure by a situ chemical oxidation synthesis method. The combination of metal oxide of the hollow porous nanocube structure and the core-shell structure formed by highly conductive PPy shell significantly enhanced heterogeneous interfaces and electromagnetic (EM) wave reflection. Excellent dielectric loss and impedance matching contributed evidently to the ultra-wideband EM wave absorption performance. It was demonstrated that, with a filling amount of only 20 wt%, the prepared Mn2O3-Fe3O4@PPy achieved an effective bandwidth (EAB) of 10.0 GHz at a thickness of 3.08 mm, with EABmax reaching 13 GHz. At a filling amount of only 10 wt%, the reflection loss (RL) was −62.13 dB, achieving an EAB of 7.4 GHz at 2.98 mm thickness, with EABmax reaching 11.4 GHz. Furthermore, the proposed strategy incorporating metal oxide and PPy enhanced corrosion resistance with higher charge transfer resistance.

Preparation of hollow CoFe Prussian blue analogues and their derived CoP-FeP nanoboxes as efficient electrocatalysts as oxygen evolution reactions

Reasonably designing and constructing transition metal based compounds with controllable composition and structure is a promising option for obtaining economically efficient oxygen evolution reaction (OER) electrocatalysts. This paper presents a one-pot self-templated epitaxial growth, phase transition and self-dissolution strategy for constructing hollow nanoboxes/solid nanocubes of CoFe bimetallic Prussian blue analogues (PBAs). The CoFe mixed phosphide with a porous hollow nanoboxes structure obtained after subsequent phosphating heat treatment exhibite enhanced OER electrocatalytic activity in alkaline media, exhibiting a low overpotential of 230 mV and a Tafel slope of 35.5 dec−1 at 10 mA cm−2, as well as excellent stability for 48 h. The excellent OER activity of CoP-FeP nanoboxes (CoP-FeP NBs) can be attributed to the combination effect between their composition and structure. Structurally, the exquisite porous hollow nanoboxes structure greatly expands the surface area, reduces ion diffusion pathways, and reduces charge transfer resistance. Compositionally, the inner transition metal phosphide exhibits good conductivity and undergoes surface reconstruction during OER, forming high valence Co(Fe)OOH active substances in situ. The strong interface coupling effect of CoOOH/FeOOH optimizes the electronic structure. This work presents a facile and efficient strategy for the construction of PBAs hollow structural materials and the exploitation of low-cost and efficient electrocatalysts.

Core-shell porous LM/TPU fibers with tunable conductive properties for use as strain and pressure sensors

Flexible wearable sensors have attracted widespread attention in health monitoring, human-machine interaction, and biomedical applications. However, developing a flexible sensor that possesses high sensitivity, wide detection range, and matches the conductive material with the modulus of elasticity remains challenging. Here, we developed a coaxial wet spinning process to fabricate conductive fibers with a core-multi-hollow-shell structure, termed LHPTF. The shell comprises a hollow porous structure of TPU, while the core consists of gallium-based LM with excellent electrical conductivity. LHPTF fibers exhibit electrical conductivity of 8690 S cm−1, high flexibility, appropriate strength, and high elongation at break. The hollow porous structure of TPU fibers can be adjusted with various hollow diameters, thereby enabling the switching between stable conduction and strain sensing of conductive fibers. Due to the protection provided by TPU, LHPTF fibers exhibit good environmental durability and stability. We also demonstrate the application of these fibers in wearable sensors and stable conductor.

In Situ Construction of Hollow Coral-Like Porous S-Doped g-C3N4/ZnIn2S4 S-Scheme Heterojunction for Efficient Photocatalytic Hydrogen Evolution.

The rational design of visible-light-responsive catalysts is crucial for converting solar energy into hydrogen energy to promote sustainable energy development. In this work, a C─S─C bond is introduced into g-C3N4 (CN) through S doping. With the help of the flexible C─S─C bond under specific stimuli, a hollow coral-like porous structure of S-doped g-C3N4 (S-CN) is synthesized for the first time. And an S-doped g-C3N4/ZnIn2S4 (S-CN/ZIS) heterojunction catalyst is in situ synthesized based on S-CN. S0.5-CN/ZIS exhibits excellent photocatalytic hydrogen evolution (PHE) efficiency (19.25mmol g-1 h-1), which is 2.7 times higher than that of the g-C3N4/ZnIn2S4 (CN/ZIS) catalyst (8.46mmol g-1 h-1), with a high surface quantum efficiency (AQE) of 34.43% at 420nm. Experiments and theoretical calculations demonstrate that the excellent photocatalytic performance is attributed to the larger specific surface area and porosity, enhanced interfacial electric field (IEF) effect, and appropriate hydrogen adsorption Gibbs free energy (ΔGH*). The synergistic effect of S doping and S-scheme heterojunction contributes to the above advancement. This study provides new insights and theoretical basis for the design of CN-based photocatalysts.

Fluorinated Hollow Porous Carbon Spheres as High-Performance Cathode Material for Primary Battery

Fluorinated carbon cathode materials have extremely high theoretical specific energy among known cathode materials of lithium primary batteries. Nevertheless, current fluorinated carbon cannot meet the performance demands of future applications due to the rate performance. This work innovatively applies hollow carbon spheres with a porous structure as carbon sources to prepare fluorinated hollow porous carbon spheres (FHPCS) with high energy density and power density. The porous structure provides more reaction sites for the fluorination process and also shortens the diffusion path of lithium ions during the discharge. Additionally, the hollow porous structure offers more interfacial contact areas and reduces volumetric expansion during discharge reactions. The Li/CFx primary battery has a maximum specific energy of 2007 Wh kg−1 and a maximum power density of 30,400 W kg−1 and can have a capacity retention rate of 80.8% at a current density of 16 A g−1. In addition, FHPCS also has the highest specific energy of 1999 Wh kg−1 and 1711 Wh kg−1 in Na/CFx and K/CFx primary batteries, respectively. The diffusion efficiency of an alkali metal ion is analyzed by the different discharge depths with electrochemical impedance spectroscopy and galvanostatic intermittent titration technique. This effort introduces a new high-performance fluorinated carbon featuring a hollow porous structure and puts forward an innovative approach to designing fluorinated carbon materials.

Unveiling the Interfacial Species Synergy in Promoting CO2 Tandem Electrocatalysis in Near-Neutral Electrolyte.

The interfacial species-built local environments on Cu surfaces impact the CO2 electroreduction process significantly in producing value-added multicarbon (C2+) products. However, intricate interfacial dynamics leads to a challenge in understanding how these species affect the process. Herein, with ab initio molecular dynamics (AIMD) and finite element method (FEM) simulations, we reveal that the highly concentrated interfacial species, including the *CO, hydroxide, and K+, could synergistically promote the C-C coupling on the one-dimensional (1D) porous hollow structure regulated interfacial environment. The Cu-Ag tandem catalyst was then synthesized with the as-designed structure, exhibiting a high C2+ Faradaic efficiency of 76.0% with a partial current density of 380.0 mA cm-2 in near-neutral electrolytes. Furthermore, in situ Raman spectra validate that the 1D porous structure regulates the concentration of interfacial CO intermediates and ions to increase *CO coverage, local pH value, and ionic field, promoting the CO2-to-C2+ activity. These results provide insights into the design of practical ECR electrocatalysts by regulating interfacial species-induced local environments.

Biotemplate synthesis of SnO2 hollow porous structures for enhanced isopropanol sensing performance

Researchers are showing significant interest in the development of nanostructures with hierarchical porosity. This study introduces an eco-friendly, cost-effective, and straightforward method to create SnO2 hollow porous nanostructures using the peony as a biotemplate. A comprehensive analysis of the gas sensing characteristics of these hierarchical SnO2 hollow porous nanostructures is conducted. The results show that the gas sensor based on SnO2 showcases relatively high response values measuring 18.3 and exhibits rapid response speed of 1 s to 100 ppm isopropanol, even at a comparably low operating temperature of 180 °C. Additionally, the sensor displays good repeatability and long-term stability, which can be attributed to the inherent advantages stemming from its distinct structure. Therefore, this study provides experimental and theoretical foundations for the potential application of hollow porous SnO2 structures in sensor technology.

Multi-shelled hollow porous carbon nanospheres-based evaporator for highly efficient solar-driven desalination

Carbon-based materials stand out as photothermal materials for interfacial solar evaporation due to their high solar absorptance, chemical stability, adjustable structure, ease of preparation, and low cost compared to other candidate materials. Development of multifunctional carbon-based materials that can endow the fabricated evaporators with reduced energy loss and evaporation enthalpy is highly demanded to achieve extraordinary evaporation rates. Herein, high-solar-absorptivity multi-shelled hollow porous carbon nanospheres are fabricated and incorporated with an insulating hydrogel bottom layer into an integrated solar evaporator. It achieves a fast photothermal response and a remarkably high solar evaporation rate of 2.4 kg m−2 h−1 under one sun. Multiphysics simulation indicates that the porous multi-shelled hollow structure enables sufficient and effective interactions between water and the hydrophilic carbon surfaces, thus producing more intermediate water (IW) and lowering the evaporation enthalpy. The solar-driven water evaporation in the evaporator is probed by in-situ low-field nuclear magnetic resonance relaxation time measurements, based on which conversion of free water (FW) into IW during solar evaporation is proposed. The molecular dynamics simulations reveal that the evolution of FW clusters into IW is facilitated on the carbon surface, thus replenishing the evaporated IW and maintaining continuous high evaporation rates. The demonstrated solar evaporator exemplifies the effectiveness of structural and thermal management in enhancing solar-driven desalination.

Simultaneously Improving Energy Storage and Oxygen Evolution Reaction by Causing Regional Defects in MOF-on-MOF Derived Hollow Se-Doped CoP-Fe2P Heterojunctions.

Doping heteroatoms into metal phosphides to modify their electronic structure is an effective method, but the incomplete exposure of active sites is its inherent drawback. In this experiment, both Se doping and P vacancies are simultaneously introduced into CoP-Fe2P (named CoFe-P-Se) to enhance the internal reactivity. Benefiting from the unique hollow porous structure derived from the MOF-on-MOF template, as well as the enhanced intrinsic activity achieved by P defects and Se doping, CoFe-P-Se exhibits a high specific capacitance of 8.41 F cm-2 at a current density of 2 mA cm-2 when used as a supercapacitor electrode. When assembled into a hybrid supercapacitor with activated carbon, the energy density reaches 0.488 mWh cm-2 at a power density of 1.534 mW cm-2, and the capacity retention after 5000 charge-discharge cycles is as high as 90.65%. As an oxygen evolution reaction (OER) electrode, the CoFe-P-Se electrode shows a low overpotential of only 230 mV at a current density of 10 mA cm-2 and 278 mV at 100 mA cm-2. Additionally, it exhibits excellent stability for over 50 h at a current density of 100 mA cm-2. The designed element doping and vacancy engineering in this work will provide an insight for constructing high-performance electrodes.

A high potential (2.5 V) carbon fiber paper-based asymmetric supercapacitor with oxygen vacancies and hierarchical porous hollow structure

The inherent limited energy density in supercapacitors constitutes a substantial impediment to their widespread adoption and large-scale production. In this study, we have devised a novel cathodic electrode denoted as OV-TiO2-X@HPHCFP, featured with rich oxygen vacancies and its hierarchical porous hollow structure. The OV-TiO2-X@HPHCFP cathode manifests an impressive areal capacitance of 1608.2 mF cm−2 at the current density of 2 mA cm−2, coupled with a remarkable capacitance retention of 97.7 % after 10,000 charge–discharge cycles. Theoretical calculations corroborate that the presence of oxygen vacancies enhances the conductivity of the electrode, facilitating expedited charge transfer kinetics. Furthermore, the electrode integrated into a double electrolyte flexible supercapacitor configuration, denoted as OV-TiO2-X@HPHCFP//PVA-Na2SO4/PVA-LiCl//OV-MoO3-Y@CFP, operated at an effective potential of 2.5 V, can yield an energy density of 1.96 × 10−1 mWh cm−2 at a power density of 1.25 mW cm−2. This investigation thereby delineates a promising strategy for the development of supercapacitors that can attain elevated operational potentials with concomitant enhancements in energy density.

Core-sheath PVDF hollow porous fibers via coaxial wet spinning for energy harvesting

Flexible piezoelectric nanogenerators (PENGs), as a promising sustainable power source in smart electronics, have attracted much attention for their potential applications in the Internet of Things. In this paper, poly(vinylidene fluoride) (PVDF) fibers with core-sheath hollow porous structure were prepared by coaxial wet spinning process, serving as the dielectric layer, which were perfused internally by liquid metal (LM) as the inner electrode layer and wrapped outside by copper-silver nanoparticles (Cu@AgNP) as the outer electrode layer, thus constructing high-performance PVDF/LM/Cu@AgNP composite fibers. The composite PVDF fibers have a layered pore structure and arbitrarily deformable LM electrodes, which can significantly reduce the effective electric constant and thus enhance the piezoelectric properties. The results reveal that PVDF/LM/Cu@AgNP-PENG yields an optimal voltage output of 410 mV, providing a clear advantage over PENG by using alternative fibers. Moreover, the PVDF/LM/Cu@AgNP-PENG shows an excellent charging capability for energy storage devices, being able to charge 1 μF capacitors to 10 V within 30 s and directly power commercial LEDs. This study demonstrates the significant potential for utilizing composite PVDF piezoelectric fibers in flexible wearable electronic devices.

Topological Polymer Networks-Enabled Mechanically Strong Polyamide-Imide Aerogel Fibers for Thermal Insulation in Harsh Environments.

Aerogel fibers have sparked substantial interest as attractive candidates for thermal insulation materials. Developing aerogel fibers with the desired porous structure, good knittability, flame retardancy, and high- and low-temperature resistance is of great significance for practical applications; however, that is very challenging, especially by using an efficient method. Herein, mechanically strong and flexible aerogel fibers with remarkable thermal insulation performance are reported, which are achieved by constructing stiff-soft topological polymer networks and a multilevel hollow porous structure. The combination of polyamide-imide (PAI) with stiff chains and polyurethane (PU) with soft chains is first found to be able to form a topological entanglement architecture. More importantly, multilevel hollow pores can be constructed synchronously through just a one-step and green wet-spinning process. The resultant PAI/PU@340 aerogel fibers show an ultrahigh breaking strength of 94.5 MPa and superelastic property with a breaking strain of 20%. Furthermore, they can be knitted into fabrics with a low thermal conductivity of 25 mW/(m·K) and exhibit attractive thermal insulation property under extremely high (300 °C) and low temperatures (-191 °C), implying them as promising candidates for next-generation thermal insulation materials.

Atomically dispersed Au single sites and nanoengineered structural defects enable a high electrocatalytic activity and durability for hydrogen evolution reaction and overall urea electrolysis

The development of exceptionally active and stable trifunctional electrocatalysts is essential to facilitate industrial applications of proton exchange membrane electrolyzers. Rare earth catalysts have a wide range of applications in alkaline solution oxidation, but limitations in their stability and activity prevent their further application. In this paper, Au doped CeO2 coated porous Aux/CeO2 (x = 1,2,3) was designed as a three-function electrocatalyst with excellent performance and stability. At 1 M KOH conditions, both the oxygen evolution reaction (OER) and the hydrogen evolution reaction (HER) reactions exhibit excess potentials of 159.6 and 320.8 mV at a current density of 10 mA cm-2. In addition, when incorporated into an Au2/CeO2 (0.05 mmol, HAuCl4·4H2O) microparticles, the catalyst exhibits the potential of 1.42 V(10 mA cm-2) containing 0.33 M urea in 1 M KOH. Remarkably, for hydrogen production driven by urea electrolysis, Au2/CeO2 demonstrated exceptional performance by requiring only a voltage input of 1.63 V. The reducing agent that forms the Au/CeO2 heterojunction modulates the electronic structure of the Au active site and optimizes the adsorption of the intermediate. In addition, the interaction of the Au monolayer with the CeO2 nanosphere effectively prevents excessive oxidation and dissolution of Au, and the porous hollow structure provides additional exposed active sites and facilitates mass transfer.

Nanoscopic catalyst-loaded porous metal oxide hollow frameworks using porous block copolymer templates for high performance formaldehyde sensors

Porous and hollow nanostructures functionalized with nanoscopic catalysts have attracted considerable interest in a wide range of applications depending on surface reactions. In this study, we present an efficient and versatile synthetic strategy of porous metal oxide hollow frameworks (HFs) decorated with noble metal nanoparticles (NPs). The key lies in the use of porous and bicontinuous polystyrene-block-poly(4-vinylpyridine) (PS-b-P4VP) microparticles as templates, which feature pores on the order of several hundred nanometers in size. Homogeneous Pt loading on the surface of the porous microparticles is achieved through the preferential adsorption of Pt precursors onto the P4VP block via electrostatic interactions. Subsequent SnO2 thin film deposition and calcination ultimately yield honeycomb-like SnO2 HFs with macropores and uniform distribution of Pt NPs. The Pt NP-loaded SnO2 HFs exhibit exceptional formaldehyde (HCHO) sensing capabilities, characterized by remarkable sensitivity (31.4 at 5 ppm), rapid response time (4.7 s at 5 ppm), ultra-low detection limit of 10 ppb, and remarkable cross-selectivity. These outstanding features result from their high surface area, gas permeability within porous hollow structures, and well-dispersed Pt NPs, which catalytically activate the sensor. Our study provides great promise for advancing surface catalytic reactions due to their exceptional surface area and gas permeability, paving the way for future applications.

Facile fabrication of cyclotriphosphazene crosslinked quercetin hollow nanocapsules by dual catalyst strategy for superfast and efficient removal of crystal violet over a wide pH range

A novel cyclotriphosphazene crosslinked quercetin (QuH) nanoadsorbent was manufactured at room temperature through precipitation copolycondensation between quercetin and hexacyclotriphosphazene (HCCP) with the help of dual catalyst. The obtained QuH had a hollow porous structure with specific surface area of 30.18 m2 g−1, an average diameter of 178 nm, and a huge negative surface charge. The adsorption efficiency of QuH was evaluated using water sample polluted with cationic dye crystal violet (CV). Results revealed that the QuH nanoadsorbent delivered an amazing adsorption amount of 840 mg g−1 within one minute and an equilibrium adsorption capacity of 1159 mg g−1 in 120 min for CV at 298.15 K and an initial CV concentration of 300 mg L−1. Moreover, the nanoadsorbent kept a high adsorption ability for CV over a wide pH range of 3–9. The coexisting ion Na+ could promote the CV adsorption, whereas Ca2+ inhibited the CV adsorption. The retention of adsorption capacity could be up to 96 % after five cycles. The superior adsorption performance of QuH for CV was proposed to be the collaborative contribution of electrostatic interaction, ion exchange, hydrogen bonding, π-π stacking and pore filling effect based on the study of adsorption kinetics, isotherm, thermodynamics, and mechanism analysis.

Porous hollow sphere structure PrFeO3 as an efficient sensing material for n-butanol detection

N-butanol is a harmful volatile gas, so creating an appropriate n-butanol sensor is critical for preserving human health and the manufacturing environment. In contrast to single metal oxide semiconductors, multicomponent metal oxides, especially perovskite ternary metal oxides with the ABO3 structure, exhibit significant potential for development owing to their precise structures and diverse physicochemical properties. In this paper, three-dimensional porous hollow spheres PrFeO3 were synthesized by combining air annealing and hydrothermal techniques. The crystal structure, surface composition, chemical state, and morphology of PrFeO3 materials were evaluated using several kinds of characterization approaches. The gas sensitivity of PrFeO3 materials was also thoroughly explored. The results show that at the optimal working temperature of 280 ℃, the PrFeO3 material excels in n-butanol gas sensing, with a response of 85 for 100 ppm n-butanol. Additionally, the sensor demonstrates high selectivity for n-butanol gases, low concentration detection capability, outstanding repeatability, rapid reaction recovery time (18 s/13 s), long-term stability, and exceptional reproducibility. The unique morphology and high oxygen vacancy content of PrFeO3 provide numerous active sites on its surface, promoting the adsorption and desorption of n-butanol gas molecules and enhancing its gas-sensitive properties.

Active release of diatomite-MgAl-layered double hydroxide nanostructures on corrosive inhibitors to effectively suppresses corrosion of LA51 alloy

Two-dimensional (2D) materials have been potentially applicable for the corrosive resistance of alloys in corrosive media. Nevertheless, a challenge remains in adapting the 2D nanomaterial layered double hydroxide (LDH) with diatomaceous earth (DE) as two inorganic nanocontainers homogeneously combined and loaded with controlled release corrosion inhibitors. In this research, the high-efficiency anti-corrosion nanofiller for LA51 alloy protection was obtained by integrating MgAl-LDH with Sodium phosphate (SP) utilizing the unique hollow porous structure of DE as a template. As a result, the incorporation of DE-LDH-P provides a 3-order of magnitude enhancement in coating immersion in 3.5 wt% NaCl solution for 40 days compared to pure epoxy. Furthermore, two nanocontainers of DE and LDH with corrosion inhibitor loading up to 15 wt% still demonstrated excellent corrosive protection after 120 h of salt spray. The key to its protective performance is promoting controlled corrosion inhibitor release through a scientific approach that fully utilizes the slow-release properties of DE and LDH. This strategy offers a straightforward and effective approach for formulating anti-corrosion additives tailored for use in corrosive settings, with potential applications across various industrial sectors. Specifically, we advocate for the utilization of maritime instrumentation, underwater armaments, and seawater-based power sources within the domains of ship construction and marine engineering.

Reactive P and S co-doped porous hollow nanotube arrays for high performance chloride ion storage

Developing stable, high-performance chloride-ion storage electrodes is essential for energy storage and water purification application. Herein, a P, S co-doped porous hollow nanotube array, with a free ion diffusion pathway and highly active adsorption sites, on carbon felt electrodes (CoNiPS@CF) is reported. Due to the porous hollow nanotube structure and synergistic effect of P, S co-doped, the CoNiPS@CF based capacitive deionization (CDI) system exhibits high desalination capacity (76.1 mgCl– g–1), fast desalination rate (6.33 mgCl– g–1 min–1) and good cycling stability (capacity retention rate of > 90%), which compares favorably to the state-of-the-art electrodes. The porous hollow nanotube structure enables fast ion diffusion kinetics due to the swift ion transport inside the electrode and the presence of a large number of reactive sites. The introduction of S element also reduces the passivation layer on the surface of CoNiP and lowers the adsorption energy for Cl– capture, thereby improving the electrode conductivity and surface electrochemical activity, and further accelerating the adsorption kinetics. Our results offer a powerful strategy to improve the reactivity and stability of transition metal phosphides for chloride capture, and to improve the efficiency of electrochemical dechlorination technologies.