Hierarchical Nanoporous Research Articles

Homologous Temperature Regulated Hierarchical Nanoporous Structures by Dealloying.

Nanoporous metals, fabricated via dealloying, offer versatile applications but are typically limited to unimodal porous structures, which hinders the integration of conflicting pore-size-dependent properties. A strategy is presented that exploits the homologous temperature (TH)-dependent scaling of feature sizes to generate hierarchical porous structures through multistep dealloying at varied TH levels, adjusted by altering dealloying temperatures or the material melting points. This technique facilitates the creation of monolithic architectures of bimodal porous nickel and trimodal porous carbon, each characterized by well-defined, self-similar bicontinuous porosities across distinct length scales. These materials merge extensive surface area with efficient mass transport, showing improved current delivery and rate capabilities as electrodes in electrocatalytic hydrogen production and electrochemical supercapacitors. These results highlight TH as a unifying parameter for precisely tailoring feature sizes of dealloyed nanoporous materials, opening avenues for developing materials with hierarchical structures that enable novel functionalities.

Ultra-high Capture of Radioiodine With Zinc Oxide-decorated, Nitrogendoped Hierarchical Nanoporous Carbon Derived From Sonicated ZIF-8-Precursor

Ultra-high Capture of Radioiodine With Zinc Oxide-decorated, Nitrogendoped Hierarchical Nanoporous Carbon Derived From Sonicated ZIF-8-Precursor

Three-dimensional hierarchical nanoporous (Mn,Ni)-Doped Cu2S architecture towards high-efficiency overall water splitting

Dealloying technique is an important approach to design porous structures and highly active catalysts. In this work, monolithic nanoporous (Mn,Ni)-doped Cu 2 S skeletons with controllable composition and tunable porosity are synthesized via dealloying and sulfuration technique. The as-prepared S-np-Mn 70 Cu 29 Ni 1 electrode exhibits outstanding catalytic performance toward HER and OER in 1.0 M KOH solution, which drives high current density of 50 mA cm −2 at the overpotentials of 136 and 317 mV respectively. The excellent catalytic performance is attributed to the unique three-dimensional interconnected bicontinuous nanoporous architecture, which not only exposes high-density catalytic active sites, but also accelerates electron/mass transfer between catalyst surface and electrolyte. Density functional theory (DFT) calculations also reveal that (Mn,Ni)-doped Cu 2 S matrix can accelerate water adsorption/dissociation and optimize adsorption-desorption energetics of H intermediates, thus improving the intrinsic HER activity of nanoporous Cu 2 S electrocatalysts. Meanwhile, an alkaline water electrolyzer is constructed with the S-np-Mn 70 Cu 29 Ni 1 electrode as anode and cathode respectively, depicting remarkable performance in water electrolysis. In the light of advantages such as adjustable composition and tunable porosity in alloying-dealloying process, it offers a new vision for tuning the porosity and catalytic activities of transition metal sulfides and other active catalysts. • A chemical dealloying strategy is developed to fabricate nanoporous architecture. • Nanoporous Cu 2 S skeleton exhibits excellent HER and OER performance. • (Mn,Ni)-doped Cu 2 S can optimize energy barriers of H 2 O dissociation and H adsorption. • Water splitting performance is enhanced by morphological and electronic modulated electrode.

Electronic Interaction between In Situ Formed RuO2 Clusters and a Nanoporous Zn3V3O8 Support and Its Use in the Oxygen Evolution Reaction.

The catalytic activity and durability of RuO2 clusters toward the oxygen evolution reaction (OER) are strongly associated with their support; however, how the electronic interaction would enhance the catalytic performance is still not quite clear. Herein, hierarchical nanoporous and single-crystal Zn3V3O8 nanosheets are adopted to anchor in situ formed RuO2 clusters. X-ray photoelectron analysis reveals significant binding energy changes of both Ru and V due to the creation of strong Ru-O-V bonding interaction, which would lead to the reconstruction of the electronic structure of the Zn3V3O8 matrix and RuO2 clusters. The ultrastrong electronic interaction also results in superior OER activity, indicated by a small overpotential at 10 mA cm-2 (228 mV) and a shallow Tafel slope of 46 mV dec-1. First-principles simulation further reveals the synergistic effect derived from the unique RuO2@Zn3V3O8 couple, which effectively regulates the electronic structure for the OER process. In addition, the created interfacial chemical bond and the confined microporous structure of the Zn3V3O8 substrate could prevent the RuO2 clusters from detachment and aggregation, making the nanocomposite a promising long-term stable OER electrocatalyst.

Hierarchical 3D Cuprous Sulfide Nanoporous Cluster Arrays Self-Assembled on Copper Foam as a Binder-Free Cathode for Hybrid Magnesium-Based Batteries.

On account of easy accessibility, high theoretical volumetric capacity and dendrite-free magnesium (Mg) anode, Mg battery has a great promise to be next generation rechargeable batteries, yet still remains a challenging task in acquiring fast Mg2+ kinetics and effective cathode materials. Herein, hierarchical 3D cuprous sulfide porous nanosheet decorated nanowire cluster arrays with robust adhesion on copper foam (Cu2 S HP/CF), which is employed as a binder-free conversion cathode material for magnesium/lithium hybrid battery, delivering impressively initial and reversible specific capacity of 383 and 311 mAh g-1 at 100mA g-1 , respectively, which are obviously outperformed corresponding powder cathode in a traditional method by using polymer binder, is reported. Intriguingly, benefiting from the hierarchical nanoporous array architecture and self-assembly feature, Cu2 S HP/CF cathode shows a remarkable cycling stability with a high capacity of 129 mAh g-1 at 300mA g-1 over 500 cycles. This work not only highlights a guide for designing hierarchical nanoporous materials derived from metal-organic frameworks, but also provides a novel strategy of in situ formation to fabricate binder-free cathodes.

Dealloying-constructed hierarchical nanoporous bismuth-antimony anode for potassium ion batteries

Bi-Sb alloys are appealing anode materials for potassium ion batteries (PIBs) but challenged by their enormous volumetric variation during operation. Herein, a facile one-step dealloying protocol was devised and utilized to prepare the Bi-Sb alloys that manifest an exotic bicontinuous hierarchical nanoporous (np) microstructure ideal for volume-change mitigation and K+ transport percolation. The growth mechanism fostering the peculiar morphology of the np-(Bi,Sb) alloys was investigated and clarified via operando X-ray (XRD) and ex-situ scanning electron microscopy (SEM). In particular, the np-Bi6Sb2 electrode, optimized for comprehensive electrochemical performance, achieves decent reversible capacities and a superior lifespan, as benchmarked with the monometallic references and other Bi-Sb alloy electrodes. The (de)potassiation mechanism of the np-(Bi,Sb) alloys was studied by operando XRD and further rationalized by density functional theory (DFT) calculations, whereby a homogeneous (segregation-free) and robust two-step electrochemically-driven phase transformations’ catenation of (Bi,Sb) ↔ K(Bi,Sb)2 ↔ K3(Bi,Sb) was reliably established to substantiate the outstanding reversibility of the np-(Bi,Sb) anodes in PIBs.

Stop Four Gaps with One Bush: Versatile Hierarchical Polybenzimidazole Nanoporous Membrane for Highly Durable Li-S Battery.

Lithium-sulfur (Li-S) batteries are considered as one of the most prospective candidates for electric vehicles, due to their superior theoretical energy density and low cost. However, the issues of polysulfide ion (PS) shuttling and uncontrollable Li dendrite growth hindered their further application. Herein, a multifunctional nanoporous polybenzimidazole (PBI) membrane with well-controllable morphology was successfully designed and fabricated to address the aforementioned obstacles. In this design, the PBI membrane could offer strong chemical binding interaction with PS, thus applying dynamic adsorption toward PS as well as stable sulfur electrochemistry, which is further verified by experiments and density functional theory (DFT) simulation. Moreover, PBI membranes with high porosity and high electrolyte uptake capability can provide ample lithium storage space and abundant Li+ supplements to facilitate Li deposition and improve Li metal batteries' cyclic stability. Besides that, the PBI membrane has excellent mechanical and thermal stability and exclusive flame resistance, which guarantees the safety of the Li-S battery as well. As a result, Li-S batteries assembled with an as-developed PBI membrane demonstrated a remarkable rate capability of 780 mAh g-1 at 2C and an impressive reversible capacity of 523 mAh g-1 at 0.5C after 400 cycles, which is much higher than the commercial separators. More importantly, even with a lofty sulfur loading of 3 mg cm-2, a high discharge capacity of 744 mAh g-1 (capacity retention 93.96%, at 0.1C after 100 cycles) can also be achieved. Overall, the current study highlighted a robust material platform for stable, safe, and efficient multifunctional separators for high-performance Li-S batteries.

High-effective preparation of 3D hierarchical nanoporous interpenetrating network structure carbon membranes as flexible free-standing anodes for stable lithium and sodium storage

Ideal lithium/sodium storage requires a simple and effective design of carbon-based anodes with appropriate morphologies/microstructures and excellent flexibility. Herein, an advanced flexible interpenetrating network carbon membrane with 3D hierarchical nanopore structure is designed and fabricated inspired by porous membrane technology via nonsolvent induced phase separation (NIPS) and carbonization. The interpenetrating network structure in the carbon membrane is generated by the NIPS membrane formation process, while the 3D hierarchical nano-porous structure is obtained from polymer decomposition during carbonization. The unique synergistic effect between the even interpenetrating network structure and the developed 3D hierarchical porous structure not only ensured structural integrity of the anodes and provided a high-volume ion transmission reservoir, but also endowed carbon membranes with multiple active sites for energy storage. As flexible anodes, the resulting carbon membranes achieved enhanced electrochemical properties by showing maximum reversible capacitance of 351.8 mA h g−1 in lithium storage and 237.4 mA h g−1 in SIBs at a current density of 50 mA g−1. In both LIBs and SIBs, the carbon membranes exhibit outstanding rate performance even at a high current density of 2000 mA g−1. They also show excellent long-term cycling stability with the coulomb efficiency maintained nearly 100 % after the first few cycles. Therefore, this work provides a simple and high-effective cross-disciplinary approach through membrane technology and carbon materials for the production of high-performance, low-cost carbon membranes for large-scale application anodes.

Highly sensitive detection of dopamine based on hierarchical nanoporous NiCoO2/Ni composite

Abstract Hierarchical nanoporous (HNP) NiCoO2/Ni composite is directly fabricated by one-step dealloying of NiCoAl ternary alloy in mild alkaline solution. HNP-NiCoO2/Ni composite is composed of three dimensional interlinking ligament backbone and open hollow channels with rich mesopores and macropores penetrating through. HNP-NiCoO2/Ni possesses preferable structure advantages to construct sensing platform in term of large surface area, robust multimodal porous architecture, as well the incorporation of well conductive Ni. As is expected, exceptional electrochemical sensing performances are achieved over HNP-NiCoO2/Ni with high sensitivity, superior selectivity, and long term durability toward DA assay even without any activation pretreatment. Especially, HNP-NiCoO2/Ni exhibits a wide linear detection range from 1 to 800 μM with a rapid response in ~2.8 s and a detection limit as low as 0.12 μM. Furthermore, HNP-NiCoO2/Ni also shows a good anti-interference toward DA detection in the presence of AC, glucose, H2O2, Cl−, K+, and Na+. Along with the merits of simple preparation, low cost, and excellent electrocatalytic performances, the as-prepared HNP-NiCoO2/Ni presents promising application potential to construct highly sensitive electrochemical sensors for DA assay.

Effect of Boron in a Hierarchical Nanoporous Layer Formation on Silicate Glass.

A hierarchical nanoporous layer (HNL) can be formed on the silicate glass surface by simple alkali etching. Though it reportedly exhibits various useful functions, such as superhydrophilicity, optical anti-reflection, and material impregnation, the principle of its formation still remains unclear. In this study, HNL formation behavior was experimentally investigated while using scanning electron microscope (SEM) and X-ray photoelectron spectroscopy (XPS) to clarify the role of boron contained in glass. As a result, it was found that HNL formation was significantly promoted by boron, which was rapidly eluted prior to alkali and alkaline earth metals. This suggests that boron, which forms the skeleton structure of glass together with Si and O, elutes to partially decompose the skeleton, and extends the elution route for HNL formation.

Guided Assembly of Well-Defined Hierarchical Nanoporous Polymers by Lewis Acid-Base Interactions.

Three-dimensional hierarchical nanoporous polymers and carbon nanomaterials with well-defined superstructures are of great interest for various intelligent applications, whereas a facile and versatile approach to access those materials with a high surface area, stable well-defined morphology, and ordered pores still remains a significant challenge. Herein, we report a self-regulated Lewis acid-base interaction-mediated assembly strategy for the in situ synthesis of morphology-engineered hyper-cross-linked porous polymers and carbon materials. A series of functionalized aromatic compounds (FAC) is subjected to self-cross-linking via classic Friedel-Crafts chemistry to achieve stable porous polymers with a high surface area. Varying the monomer/catalyst combination had a dramatic effect on the acid-base interaction, facilitating the tailoring of the self-assembled morphologies from nanotubes to hollow nanospheres, and even nanosheets. A mechanistic study showed that the byproducts generated during cross-linking orchestrate the interactions between the catalyst (acid) and FAC (base) and simultaneously drive the self-assembly to yield specific morphologies. Based on the rigid hollow polymer framework and intrinsic hydroxyl functionality, the hyper-cross-linked hollow nanospheres were easily transformed to an acid-functionalized catalyst for efficient biodiesel production. Moreover, high-quality porous carbonaceous nanocounterparts such as carbon nanotubes, hollow carbon nanospheres, and carbon nanosheets could also be produced by direct pyrolysis of the corresponding polymer precursors. These findings may provide guidance for the facile design of morphology-controlled functionalized polymers and carbon nanomaterials for various applications.

Support-free 3D hierarchical nanoporous Cu@Cu2O for fast tandem ammonia borane dehydrogenation and nitroarenes hydrogenation under mild conditions

A support-free hierarchical nanoporous (NP) Cu@Cu2O composite is easily fabricated by dealloying Cu5Al95 alloy in dilute NaOH solution. This bulk material has a support-free spongy structure composed of three-dimensional interconnected ligaments and open pore channels with multimodal pore size distributions. The NP-Cu@Cu2O catalyst exhibits high activity, good chemoselectivity, and excellent recyclability toward one-pot transfer hydrogenation reactions of diverse nitroarenes to anilines. NP-Cu@Cu2O can effectively activate ammonia borane under mild conditions and complete the transfer hydrogenation reactions with high yields within a short time period of 5 min Cu2O formed at the nanoporous surface is proposed to be the actual active site causing this advanced performance. The main reaction intermediates were successfully separated and characterized, and a plausible condensation mechanism has been proposed for nitro reduction.

Hierarchical Nanoporous Carbon Templated and Catalyzed by the Bicontinuous Nanoporous Copper for High Performance Electrochemical Capacitors

AbstractTo enhance the performance of electrochemical capacitor, the nanostructured carbon materials with large surface area, appropriate pore distributions, suitable electronic conductivity and perfect chemical stability are pursued. Herein, the highly graphitized hierarchical porous carbon with well‐defined porosity are fabricated. For the first time, the novel bicontinuous nanoporous copper is used as both the template and the catalyst to synthesize the porous carbon materials. The as‐prepared porous carbon demonstrates a high specific surface area of 1826 m2 g−1 benefitting from the bicontinuous nanoporous copper template and KOH activation. By electrochemical test, the nanoporous carbon material displays a specific capacitance of 210 F g−1 at a current density of 0.2 A g−1 within 6 M KOH aqueous solution. The material demonstrates excellent cycling stability with a 95.4% capacity retention for 10 000 cycles with a current density of 1 A g−1. The present work provides a facile approach for fabrication of carbon‐based electrode materials for electrochemical capacitors.

Facile fabrication and optimization of bowl-like ZnO/CdS nano-composite thin films with hierarchical nanopores and nano-cracks for high-performance photoelectrochemistry

A special nano-structured composite ZnO/CdS thin film with hierarchical nanopores and nano-cracks has been synthesized by a facile two-step method for the first time, in which both loadings of ZnO and CdS are optimized. We first fabricated the hierarchical nanoporous ZnO thin film through rapid gas/liquid interface assembly and layer-by-layer transfers of bowl-like ZnO nanoparticles for thirteen times. The ZnO nanobowls are prepared by a simple solution chemical reaction without using any templates. After annealing, the assembled ZnO film is sensitized with CdS nanoparticles by successive ionic layer adsorption and reactions for six cycles. Nano-cracks form for the ZnO/CdS nano-composite film by calcination, which is due to the different thermal expansion behavior between the ZnO film and the CdS layer. The facilely optimized ZnO/CdS films can serve as a promising photoanode in a photoelectrochemical cell, and it can generate a saturated photocurrent density as high as 7.8 mA cm−2 at −0.9 V (vs. Hg|Hg2SO4|saturated K2SO4) under visible light illumination of 100 mW cm−2 in an aqueous solution of 0.5 M Na2S, corresponding to a solar-to-electricity conversion efficiency of 6.6%.

Synthetic strategy and evaluation of hierarchical nanoporous NiO/NiCoP microspheres as efficient electrocatalysts for hydrogen evolution reaction

The development of efficient hydrogen evolution reaction (HER) catalysts based on non-precious metal alternative to noble metal is significant for booming energy conversion/storage systems. Here, we report a facile strategy to design a novel hierarchical nanoporous (HNP) HER electrocatalyst by incorporating transition metal oxide (TMO) NiO and complex phosphide (TMP) NiCoP. With the HNP NiCo2O4 products via a facile solvothermal and annealing method, the NiO/NiCoP composite was easily obtained through a simple subsequent phosphorization process at the optimized temperature. Owing to various factors such as the strong synergetic coupling effects between TMO and TMP, electron interaction between TMPs, unique HNP structure features and increased active sites, the resulting HNP NiO/NiCoP composite demonstrated significantly enhanced electrocatalytic HER activities with a current density of 10 mAcm−2 at a small overpotential of 112 mV, a low Tafel slope of about 56 mV dec−1 and satisfactory stability. We expect that this facile synthetic strategy of active binary TMPs functionalized hierarchical porous TMOs will provide a promising prospect for the development of non-precious HER electrocatalysts.

A PSS‐Free PEDOT Conductive Film Supported by a Hierarchical Nanoporous Layer Glass

AbstractThe importance of transparent conductive film is increasing due to its use in applications such as touch‐panel devices. Although indium tin oxide is widely used because of its high conductivity and transparency, conductive polymers are being studied as alternative materials that avoid the use of rare metals and the brittleness associated with existing systems. Polyethylene dioxythiophene (PEDOT)/polyethylene sulfonic acid (PSS) is drawing a lot of attention due to its well‐balanced conductivity, transparency, film formability, and chemical stability. The nonconductive PSS reportedly covers the conductive PEDOT. The PSS shell provides carrier and film‐formability to PEDOT but is also a barrier that hinders electrical conductivity. Therefore, the PEDOT film formability is explored supported by a substrate without the addition of PSS. The “hierarchical nanoporous layer glass” holds the PSS‐free PEDOT with its nanopores to form a homogeneous, transparent film. The PSS‐free PEDOT film thus achieves transparency of over 85% and resistivity of below 500 Ω sq−1.

A highly sensitive and stable electrochemical sensor for simultaneous detection towards ascorbic acid, dopamine, and uric acid based on the hierarchical nanoporous PtTi alloy

In current work highly sensitive and stable electrochemical sensor for simultaneous detection of ascorbic acid (AA), dopamine (DA), and uric acid (UA) is constructed based on the hierarchical nanoporous (HNP) PtTi alloy. The HNP-PtTi alloy is simply fabricated by two-step dealloying process, characterized by the bimodal ligament/pore size distributions and interconnected hollow channels. The HNP structure with the advantages of large surface area, excellent structure stability, and rich pore channels is used for facilitating the electron conductivity and the mass transfer. Combined with the dual effects of the bimodal nanoporous architecture and the excellent electrocatalytic activity of PtTi alloy, the constructed sensor exhibits high electrochemical sensing activity with wide linear responses from 0.2 to 1mM, 0.004 to 0.5mM, and 0.1 to 1mM for simultaneous detection of AA, DA, and UA, respectively. In addition, HNP-PtTi alloy also shows long-term sensing stability towards the AA, DA, and UA detection and behaves as a good anti-interference towards NaCl, KCl, FeCl3, CuCl2, AlCl3, glucose, and H2O2. The HNP-PtTi alloy manifests intriguing application potential as the candidate for the application of the electrochemical sensor for simultaneous detection of AA, DA, and UA.

Hierarchical nanoporous PtTi alloy as highly active and durable electrocatalyst toward oxygen reduction reaction

Hierarchical nanoporous (HNP) PtTi alloy with multimodal size distributions and controllable bimetallic ratio is successfully fabricated by a simple two–step dealloying process. The as–prepared HNP–Pt75Ti25 alloy consists of interconnected bimodal nanoporous architecture with two order ligament/pore size distributions and interconnected hollow channels extending in all three dimensions. Compared with the NP–Pt and commercial Pt/C catalysts, HNP–Pt75Ti25 alloy exhibits markedly enhanced electrocatalytic activities for oxygen reduction reaction (ORR) with superior catalytic durability besides the higher specific and mass activities. X–ray photoelectron spectroscopy and density functional theory calculations demonstrate that alloying Pt with Ti (25 at.%) could bring favorable electronic perturbation with the downshifted d–band center of Pt, leading to the weakened Pt–O and Pt–OH bond as well as the improved ORR performances. The excellent electrocatalytic performances for ORR and the facile preparation render HNP–Pt75Ti25 alloy attractive as promising cathode electrocatalysts in proton exchange membrane fuel cells.

Densification of Ionic Liquid Molecules within a Hierarchical Nanoporous Carbon Structure Revealed by Small-Angle Scattering and Molecular Dynamics Simulation

The molecular-scale properties of the room temperature ionic liquid (RTIL) 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl) imide, [C4mim+][Tf2N–], confined in nanometer-scale carbon pores have been investigated using small-angle X-ray and neutron scattering and fully atomistic molecular dynamics simulations. [C4mim+][Tf2N–] densities significantly higher than that of the bulk fluid at the same temperature and pressure result from the strong affinity of the RTIL cation with the carbon surface during the initial filling of slitlike, subnanometer micropores along the mesopore surfaces. Subsequent filling of cylindrical ∼8 nm mesopores in the mesoporous carbon matrix is accompanied by weak RTIL densification. The relative size of the micropores compared to the ion dimension, and the strong interaction between the RTIL and the slit-like micropore, disrupt the bulk RTIL structure. This results in a low-excluded volume, high-RTIL ion density configuration. The observed interfacial phenomena are simulated using a molecular dynamics model consisting of a linear combination of mesopore and micropore effects. These observations highlight the importance of including the effects of a porous substrate’s internal surface morphology, especially roughness and microporosity, on the resulting electrolyte structural properties and performance in electrical energy storage applications.

A Hierarchical Nanoporous PtCu Alloy as an Oxygen-Reduction Reaction Electrocatalyst with High Activity and Durability.

A hierarchical nanoporous (HNP) PtCu alloy was successfully fabricated by two-step dealloying of a well-designed PtCuAl precursor alloy combined with an annealing operation. The as-made PtCu alloy has an interconnected hierarchical network architecture with controllable bimodal ligament/pore distributions obtained by adjusting the annealing temperature and the redealloying time. HNP-PtCu exhibits superior specific and mass activities for the oxygen-reduction reaction (ORR) compared with single-modal nanoporous PtCu and commercial Pt/C catalysts. More importantly, the HNP-PtCu alloy shows much higher structure stability with less loss of the electrochemical surface area of Pt and ORR activity upon long-term potential scans in acid solution. The excellent electrocatalytic performance for ORR makes the HNP-PtCu alloy attractive as efficient cathode electrocatalysts in fuel-cell-related technologies.