Spontaneous Gelation Research Articles

Voltammetric sensor for indole-3-lactic acid determination featuring N-doped core-shell Ir@Mo@Ni aerogels on screen printed carbon electrode

The excessive consumption of liquor accounts for 5.3% annual death and indole-3-lactic acid has been identified as a possible biomarker for mentally disorder patients arising from alcohol abuse. A highly sensitive and selective voltammetric sensing platform is proposed composed of N-doped core-shell Ir@Mo@Ni aerogel prepared via a facile in situ spontaneous gelation route using one-step NaBH4 reduction technique anchored on a cost-effective screen-printed carbon electrode (SPCE) for determination of indole-3-lactic acid (ILA) levels in buffer and serum. Prior to the analytical phase, the composite (N-Ir@Mo@Ni/SPCE) was thoroughly characterized, and different methods were used to investigate the electrochemical properties. The combination of tri-metallics resulted in improved sensing capacities in the linear range from 0.01–20µM, with sensitivity and limits of detection of 0.162 μA/μM and 7.2nM, respectively, towards ILA determination. Furthermore, the developed sensing platform was utilized for the analyses of ILA in human normal and alcohol use disorder patients’ serum samples. Liquid chromatography in tandem with mass spectrometry was equally used to quantify ILA levels in the serum samples and the results of both methods were compared.

Enhancing the Flexural Strength of AlN with an Additional Cross-Linking Mechanism in the Aqueous Isobam Gelling System.

Isobam is widely used for fabricating ceramics through spontaneous gelation and has attracted considerable interest. However, the disadvantage of the Isobam system is the low gelation strength. The effects of suitable additives and the mechanism by which they effectively enhance the green body strength and the rheological behavior of an aluminum nitride (AlN) slurry with 50 vol% solid loading were investigated using polyethyleneimine (PEI), hydantoin epoxy resin, and trimethylolpropane triglycidyl ether (TMPGE). Results showed that the additives acted as both dispersants and cross-linkers in the AlN suspension using the Isobam gelling system. The flexural strength of the AlN green body increased by 42%, 204%, and 268% with the addition of 1 wt% PEI, 1 wt% hydantoin epoxy resin, and 0.5 wt% TMPGE, respectively. After sintering at 1700 °C, the AlN ceramic with 0.5 wt% TMPGE had flexural strength and thermal conductivity of 235 MPa and 166.44 W/(m·K), respectively, showing superior performance to the ceramics without additives.

Spontaneous gelation behaviors and mechanism of Ficus awkeotsang Makino pectin

Ficus awkeotsang Makino (jelly fig) can produce edible gels by rubbing its seeds in water at room temperature in which pectin is considered as the main gelling component. However, the spontaneous gelation mechanism of Ficus awkeotsang Makino (jelly fig) pectin (JFSP) is still unclear. This study aimed to reveal the structure, physicochemical properties, and spontaneous gelation behaviors and mechanism of JFSP. JFSP was first obtained by water extraction and alcohol precipitation method, with a pectin yield of 13.25 ± 0.42 % (w/w), weight-average molar mass (Mw) of 111.26 kDa, and methoxylation degree (DM) of 26.8 %. Analysis of monosaccharide compositions showed that JFSP was composed of 87.8 % galactose acid, indicating a high percentage of galacturonic acid blocks. Measurement on the gelling capacity suggested that JFSP gels can be easily formed by simply dispersing the pectin in water at room temperature without adding any co-solutes or metal ions. Gelation force analysis indicated that hydrogen bonding, hydrophobic interactions, and electrostatic interactions were the main factors contributing to gel formation. At 1.0 % (w/v) of pectin concentration, JFSP gels exhibited relatively high gel hardness (72.75 ± 1.15 g) and good thermal and freeze-thawing stability. Overall, these findings highlight the potential application of JFSP as a promising commercial pectin resource.

Tough, low-friction and homogeneous physical hydrogel by a solvent-inducted strategy

Physical hydrogels composed of non-covalent interacting networks have received high attention for their excellent mechanical properties and environmental friendliness, and widely applied as artificial tissues. However, it remains a challenge to synthesize a tough hydrogel via a facile approach. Based on the grafting and spontaneous gelation of PVA and CBA under the mixed solvent, a highly transparent, rapidly formed organohydrogel derived from a structural network between mixed solvent was prepared, whose mechanical properties and gel rate can be regulated by the molar fraction of DMSO. The operation barely reflected phase separation and whitening from hydrophobic interactions despite the exist of water molecules. The hydrogel with crystal domain and hydrophobic domain as strong crosslinks and hydrogen bond as weak cross-linked points by a solvent-inducted strategy, was tough and low-friction. The entire preparation of hydrogel highlights a simple and efficient solvent conversion strategy suitable for gel synthesis with an interaction between polymer and solvent.

Interface and electronic structure regulation of Mo-doped NiSe2-CoSe2 heterostructure aerogel for efficient overall water splitting

Transition metal selenides (TMSes) with cubic pyrite-type crystal structure have been widely explored as electrocatalysts for oxygen evolution reaction (OER), but the insufficient hydrogen evolution reaction (HER) performance hinders the application of overall water splitting. Herein, we designed and prepared a Mo doped NiSe2-CoSe2 heterostructure aerogel as bifunctional electrocatalyst via facile spontaneous gelation and selenium vapor deposition. The active sites on the heterointerface possessed desirable Gibbs free energy of hydrogen adsorption, leading to better HER performance than single NiSe2 or CoSe2. Moreover, systematically experimental research and density functional theory (DFT) calculations revealed that fine regulated Mo doping improved the electropositivity of heterostructure, promoting the nucleophilic adsorption of water molecule. Benefit from those improvements, the optimal Mo doped NiSe2-CoSe2 aerogel exhibited an extremely low overpotential of 57 mV at the current density of 10 mA·cm−2 for HER with a small Tafel slope value of 38 mV·dec−1. Meanwhile, Mo doping provided higher electron transfer efficiency and better adsorptive property toward reaction intermediate in anodic reaction, resulting in low overpotential of 270 mV at the current density of 100 mA·cm−2 for OER with good electrocatalytic stability. This work provides an anticipated perspective of rational combination of metal doping and heterostructure for advanced electrocatalysts.

Supramolecular alternating copolymers with highly efficient fluorescence resonance energy transfer.

This article reports alternating supramolecular copolymerization of two naphthalene-diimide (NDI)-derived building blocks (NDI-1 and NDI-2) under thermodynamic control. Both monomers contain a central NDI chromophore, attached to a hydrocarbon-chain and a carboxylic-acid group. The NDI core in NDI-2 is symmetrically substituted with two butane-thiol groups, which makes it distinct from NDI-1. In decane, a 1 : 1 mixture of NDI-1 and NDI-2 shows spontaneous gelation and a typical fibrillar network, unlike the behavior of either of the components individually. The solvent-dependent UV/vis spectrum of the mixed sample in decane shows bathochromically shifted sharp absorption bands and a sharp emission band (holds a mirror-image relationship) with a significantly small Stokes shift compared to those in CHCl3, indicating J-aggregation. In contrast, the aggregated spectra of the individual monomers show broad structureless features, suggesting ill-defined aggregates. Cooling curves derived from the temperature-dependent UV/vis spectroscopy studies revealed early nucleation and a signature of well-defined cooperative polymerization for the mixed sample, unlike either of the individual components. Molecular dynamics simulations predicted the greatest dimer formation tendency for the NDI-1 + NDI-2 (1 : 1), followed by pure NDI-1 and NDI-2. Theoretical studies further revealed a partial positive charge in the NDI ring of NDI-1 when compared to NDI-2, promoting the alternating stacking propensity, which is also favored by the steric factor as NDI-2 is core-substituted with alkyl thiols. Such theoretical predictions fully corroborate with the experimental results showing 1 : 1 stoichiometry (from Job's plot) of the two monomers, indicating alternate stacking sequences in the H-bonded (syn-syn catemer type) supramolecular copolymer. Such alternating supramolecular copolymers showed highly efficient (>93%) fluorescence resonance energy transfer (FRET).

Polymer Gel with Tunable Conductive Properties: A Material for Thermal Energy Harvesting.

The spontaneous gelation of poly(4-vinyl pyridine)/pyridine solution produces materials with conductive properties that are suitable for various energy conversion technologies. The gel is a thermoelectric material with a conductivity of 2.2-5.0 × 10-6 S m-1 and dielectric constant ε = 11.3. On the molecular scale, the gel contains various types of hydrogen bonding, which are formed via self-protonation of the pyridine side chains. Our measurements and calculations revealed that the gelation process produces bias-dependent polymer complexes: quasi-symmetric, strongly hydrogen-bonded species, and weakly bound protonated structures. Under an applied DC bias, the gelled complexes differ in their capacitance/conductive characteristics. In this work, we exploited the bias-responsive characteristics of poly(4-vinyl pyridine) gelled complexes to develop a prototype of a thermal energy harvesting device. The measured device efficiency is S = ΔV/ΔT = 0.18 mV/K within the temperature range of 296-360 K. Investigation of the mechanism underlying the conversion of thermal energy into electric charge showed that the heat-controlled proton diffusion (the Soret effect) produces thermogalvanic redox reactions of hydrogen ions on the anode. The charge can be stored in an external capacitor for heat energy harvesting. These results advance our understanding of the molecular mechanisms underlying thermal energy conversion in the poly(4-vinyl pyridine)/pyridine gel. A device prototype, enabling thermal energy harvesting, successfully demonstrates a simple path toward the development of inexpensive, low-energy thermoelectric generators.

P-doped CoCu aerogel as a bifunctional electrocatalyst for efficient overall water splitting

The exploration of bifunctional transition metal-based catalysts for water electrolysis is important for clean and large-scale production of hydrogen but yet remains challenging. Herein, a novel phosphorous doped cobalt-copper aerogel (P-CoCu) with three-dimensional interconnected structure was prepared via spontaneous gelation and in-situ P doping process. The electronic structure and charge density of Co could be modulated upon alloying with Cu, resulting in optimized charge transfer efficiency and proton adsorption energy. The hydrophilicity and the bond strength of H* were further optimized through P doping, which promoted the reaction efficiency on the surface of P-CoCu. Besides, the unique porous morphology of aerogel endowed the catalyst with efficient mass transfer pathways and abundant active sites. Density functional theory (DFT) calculations further revealed the electron redistribution and the optimization of H2 desorption performance through Cu alloying and P doping. Based on the outstanding features, the optimized P-CoCu sample achieved extremely low overpotentials of 74/224 mV for hydrogen evolution reaction (HER) / oxygen evolution reaction (OER) at a current density of 10 mA·cm−2 in 1 M KOH electrolyte. Additionally, a two-electrode electrolytic cell assembled with P-CoCu only required an operating voltage of 1.57 V at 10 mA·cm−2 with decent stability, which was comparable to commercial noble-metal catalysts (Pt/C//RuO2/C) and superior to recently published electrocatalyst. This work provides an anticipated perspective of non-noble metal-based bifunctional catalysts for overall water splitting.

Spontaneous Gelation of Adhesive Catechol Modified Hyaluronic Acid and Chitosan.

Spontaneously formed hydrogels are attracting increasing interest as injectable or wound dressing materials because they do not require additional reactions or toxic crosslinking reagents. Highly valuable properties such as low viscosity before external application, adequate filmogenic capacity, rapid gelation and tissue adhesion are required in order to use them for those therapeutic applications. In addition, biocompatibility and biodegradability are also mandatory. Accordingly, biopolymers, such as hyaluronic acid (HA) and chitosan (CHI), that have shown great potential for wound healing applications are excellent candidates due to their unique physiochemical and biological properties, such as moisturizing and antimicrobial ability, respectively. In this study, both biopolymers were modified by covalent anchoring of catechol groups, and the obtained hydrogels were characterized by studying, in particular, their tissue adhesiveness and film forming capacity for potential skin wound healing applications. Tissue adhesiveness was related to o-quinone formation over time and monitored by visible spectroscopy. Consequently, an opposite effect was observed for both polysaccharides. As gelation advances for HA-CA, it becomes more adhesive, while competitive reactions of quinone in CHI-CA slow down tissue adhesiveness and induce a detriment of the filmogenic properties.

Silk fibroin hydrogel containing Sesbania sesban L. extract for rheumatoid arthritis treatment

Purpose Rheumatoid arthritis, a chronic and progressive inflammation condition in the joints, has significantly reduced the patient quality of life and life expectancy. Crucially, there is no complete therapy for this disease, and the current treatments possess numerous side effects. Thus, novel therapeutic approach is necessary. To that end, this study developed novel silk fibroin in-situ hydrogel containing Sesbania sesban L. extract, a plant with high anti-inflammatory actions that are beneficial for rheumatoid arthritis treatments. Methods The hydrogels were manufactured using simple method of spontaneous gelation at different temperature. The gel properties of morphology, gelation time, viscosity, gel strength, stability, drug loading capacity, drug release rate, and in-vitro anti-inflammatory activity were investigated with appropriate methods. Results The optimal formulation had highly porous structure, with a gelation time of 0.5 h at room temperature and bodily temperature of 37 °C, a viscosity of 2530 ± 50 cP, a gel strength of 1880.14 ± 35.10 g, and a physical stability of >6 months. Moreover, the hydrogel contained the Sesbania sesban L. leaf extract with a total phenolic content of 92.8 ± 8.30 mg GAE/g, and sustained the release rate for >20 dạys, followed the Higuchi model. Regarding the in-vitro activities, all formulations were nontoxic to the RAW 264.7 cell line and demonstrated comparable anti-inflammatory activity to the free extract, in terms of the NO reduction levels. Conclusion Conclusively, the systems possessed potential properties to be further investigated to become a prospective rheumatoid arthritis treatment.

Extraction, characterization and spontaneous gelation mechanism of pectin from Nicandra physaloides (Linn.) Gaertn seeds

Nicandra physaloides (Linn.) Gaertn seeds (NPGS) could be manually scrubbed to obtain water-soluble pectin, which forms gel at room temperature without additives. The extraction, characterization and spontaneous gelation (SG) mechanism of the pectin were studied. The results showed that the pectin was located on the surface of NPGS and easily to be dissolved. Chemically, the pectin was low methoxy pectin with esterification degree of 46.93%, Gal-A content of 65.80%, and average molar weight of 631.15 kDa. The SG occurred at the pectin concentration of 1.5%, it can be destroyed by urea and SDS, however, EDTA cannot. In addition, KCl and NaCl induced the gelation of 1.0% pectin solution and the ions of K, Mg, Ca and Na were detected in the pectin. Hydrogen bonding, electrostatic and hydrophobic interaction contributed to the SG. This study could promote the commercial applications of the pectin in the field of edible colloids and cosmetics.

Nano-Fibrous Networks from Co-Assembly of Amphiphilic Peptide and Polyelectrolyte.

Organize the matter on an increasingly small scale is sought in order to increase the performance of materials. In the case of porous materials, such as filtration membranes, a compromise must be found between the selectivity provided by this nanostructuring and a permeability in particular linked to the existing pore volume. In this work, we propose an innovative waterborne approach consisting in co-assembling peptide amphiphiles (PA) which will provide nanostructuring and polyelectrolytes which will provide them with sufficient mechanical properties to sustain water pressure. C16-V3A3K3G-NH2 PA nanocylinders were synthesized and co-assembled with poly(sodium 4-styrenesulfonate) (PSSNa) into porous nano-fibrous network via electrostatic interactions. The ratio between C16-V3A3K3G-NH2 and PSSNa was studied to optimize the material structure. Since spontaneous gelation between the two precursors does not allow the material to be shaped, various production methods have been studied, in particular via tape casting and spray-coating. Whereas self-supported membranes were mechanically weak, co-assemblies supported onto commercial ultrafiltration membranes could sustain water pressure up to 3 bars while a moderate permeability was measured confirming the existence of a percolated network. The produced membrane material falls into the ultrafiltration range with a pore radius of about 7.6 nm.

High molecular weight hyper-branched PCL-based thermogelling vitreous endotamponades

Vitreous endotamponades play essential roles in facilitating retina recovery following vitreoretinal surgery, yet existing clinically standards are suboptimal as they can cause elevated intra-ocular pressure, temporary loss of vision, and cataracts while also requiring prolonged face-down positioning and removal surgery. These drawbacks have spurred the development of next-generation vitreous endotamponades, of which supramolecular hydrogels capable of in-situ gelation have emerged as top contenders. Herein, we demonstrate thermogels formed from hyper-branched amphiphilic copolymers as effective transparent and biodegradable vitreous endotamponades for the first time. These hyper-branched copolymers are synthesised via polyaddition of polyethylene glycol, polypropylene glycol, poly(ε-caprolactone)-diol, and glycerol (branch inducing moiety) with hexamethylene diisocyanate. The hyper-branched thermogels are injected as sols and undergo spontaneous gelation when warmed to physiological temperatures in rabbit eyes. We found that polymers with an optimal degree of hyper-branching showed excellent biocompatibility and was able to maintain retinal function with minimal atrophy and inflammation, even at absolute molecular weights high enough to cause undesirable in-vivo effects for their linear counterparts. The hyper-branched thermogel is cleared naturally from the vitreous through surface hydrogel erosion and negates surgical removal. Our findings expand the scope of polymer architectures suitable for in-vivo intraocular therapeutic applications beyond linear constructs.

Amorphous aerogel of trimetallic FeCoNi alloy for highly efficient oxygen evolution

Developing highly efficient, cost-effective and extremely stable electrocatalysts toward oxygen evolution reaction (OER) is a great challenge for their promising water splitting application to promote the sluggish kinetics. In this work, an amorphous non-noble FeCoNi trimetallic aerogel (FeCoNi AG) is prepared via a one-step in situ spontaneous gelation and reduction strategy, presenting a remarkable OER activity and stability in an alkaline medium. FeCoNi AG catalyst delivers an exceptionally low overpotential of 235 mV at a current density of 10 mA cm−2 and features a small Tafel slope of 50 mV dec-1 in 1 M KOH, which is superior to the state-of-the-art RuO2 and many other reported transition FeCoNi-based catalysts. In addition, an outstanding long-term durability during 40 h chronoamperometric test and 5000 cyclic voltammetry (CV) cycles without obvious degradation of current density is achieved. This work is of high inspiration for developing transition metals-based amorphous aerogel electrocatalysts for greatly enhanced oxygen evolution.

FUNCTIONAL MATERIALS FROM PAPER WASTES. II. CELLULOSE HYDROGELS WITH HIGH WATER RETEN-TION CAPACITY OBTAINED FROM SOLUTIONS OF WASTE PAPER IN DMAC/LiCl

An efficient process for recycling paper and cardboard wastes via dissolution in N,N-dimethylacetamide/lithium chloride (DMAc/LiCl) system and regeneration from solutions to obtain hydrogels has been developed. Pretreatment of waste paper has been carried out by thermal defibrillation of waste paper in water and homogenization to obtain fibre samples. The dissolution of fibre materials has been performed in two ways varying the process temperature and the way the reagents have been introduced. Regeneration from solutions has been carried out by spontaneous gelation without the use of antisolvents, at room temperature and atmospheric pressure. As a result, hydrogels were obtained which differed in color and transparency depending on feedstock. The physico-chemical properties of the hydrogels have been characterized. It has been shown that they were stable in an aqueous medium, capable of retaining a significant amount of water (over 4000 wt.%), and were porous systems which has been confirmed by scanning electron microscopy. According to a wide-angle X-ray scattering, the crystallographic structure of the pristine waste paper samples corresponded to a structural modification of cellulose I. Regenerated samples as freeze-dried hydrogels had the structure of cellulose II. A functional and an elemental composition studied with FTIR spectroscopy and an energy-dispersive X-ray microanalysis characterized these hydrogels as the cellulose samples containing small amount of inorganic impurities. The resulting hydrogels had a system of through pores of different sizes, and this predetermined their use as adsorbents and active matrices.

Spontaneous three-dimensional self-assembly of MXene and graphene for impressive energy and rate performance pseudocapacitors

Integration of pseudocapacitive nanomaterials within graphene based 3D-hydrogel network has shown suitable synergist in rate performance energy storage, but implementing the same with MXene through conventional heat involved processing is challenging due to its oxidation prone surface. Herein, we present a purely room temperature casting based approach to develop 3D-hydrogel hybrids of MXene and graphene (MGH) via metallic zinc particles induced spontaneous gelation, avoiding oxidation possibility. MGH was used as supercapacitor electrode that exhibits high mass specific capacitance of 357 F g–1 at 10 mV s–1, and excellent capacity retention of 95.6% after 10000 charge-discharge cycles. MGH was used as negative electrode to develop asymmetric supercapacitor, in combination with polyaniline (PANI)-graphene hybrid hydrogel (PGH) as positive electrode, that delivers a maximum energy density of 30.3 Wh kg–1 and a power density of 1.13 kW kg–1 with excellent capacity retention over 10000 cycles. In comparison to compact electrodes where pseudocapacitive materials cannot display their faradic activity with full potential, the hydrated porous network of MXene-graphene hydrogels with continuous channels permit the electrolyte ions to efficiently access MXene and PANI, thereby displaying high gravimetric and rate performance. MXene-graphene hydrogels, developed via this facile and cost effective protocol, are also attractive candidate for wide application areas that requires 3D porous structure.

Polymer-free hydrogel made of lipid nanocapsules, as a local drug delivery platform

Nanoparticle-loaded hydrogels are attractive pharmaceutical drug delivery systems that combine the advantages of both hydrogel (local administration and/or sustained drug release) and nanoparticle (stealthiness, targeting and decreased toxicity). The design of nanoparticle-loaded hydrogels is largely conventional, consisting of the dispersion of nanoparticles in a natural or synthetic polymer matrix to form a gel network. Novel nanoparticle-loaded hydrogels architecture could provide advantages in terms of innovation and application. We focused on the development of lipid nanocapsule (LNC)-based hydrogels without the use of a polymer matrix as a platform for drug delivery. Cytidine was modified by grafting palmitoyl chains (CytC16) and the new entity was added during the LNC phase-inversion formulation process allowing spontaneous gelation. Positioned at the oil/water interface, CytC16 acts as a crosslinking agent between LNCs. Association of the LNCs in a three-dimensional network led to the formation of polymer-free hydrogels. The viscoelastic properties of the LNC-based hydrogels depended on the LNC concentration and CytC16 loading but were not affected by the LNC size distribution. The LNC and drug-release profiles were controlled by the mechanical properties of the LNC-based hydrogels (slower release profiles correlated with higher viscoelasticity). Finally, the subcutaneous administration of LNC-based hydrogels led to classic inflammatory reactions of the foreign body-reaction type due to the endogenous character of CytC16, shown by cellular viability assays. New-generation nanoparticle-loaded hydrogels (LNC-based polymer-free hydrogels) show promise as implants for pharmaceutical applications. Once LNC release is completed, no gel matrix remains at the injection site, minimizing the additional toxicity due to the persistence of polymeric implants. Sustained drug-release profiles can be controlled by the mechanical properties of the hydrogels and could be tailor-made, depending on the therapeutic strategy chosen.

Investigation of gelation mechanism and the effects of APS on AlN slurries with Isobam

A novel and simple gelling system based on a water-soluble copolymer of isobutylene and maleic anhydride (commercial name, Isobam) was adopted to manufacture various ceramics via spontaneous gelation. The gelation mechanism of AlN slurry was investigated using infrared spectroscopy. Results show that Isobam was hydrolyzed to produce the –COOH group, and the hydrogen bonding was formed between the –COOH and –CONH2 groups of Isobam during spontaneous gelation. Meanwhile, the gelling process of the Isobam system could be accelerated via enhancing hydrogen bonding through APS addition. With 1 wt% addition of APS, the gelation time reduced to 23 h, the viscosity of 50 vol% AlN slurry decreased to 0.21 Pa·s, and the flexural strength of green body improved by 48%. Therefore, the presence of hydrogen bonding in the Isobam gelation mechanism was confirmed, and it could be enhanced by introducing APS to accelerate gelation.

Thermoinduced aggegation of chitosan systems in perikinetic and orthokinetic regimes

Thermoresponsive colloidal chitosan systems forming the polymer structure in situ are an example of promising solutions in tissue engineering as an injectable scaffolds or drug carriers. Their application method, and thus shearing, may affect the aggregation process in accordance with the colloidal engineering approach. The aim of the study is to compare the kinetics of chitosan aggregation in the perikinetic regime (limited by Brownian motions) with the orthokinetic process carried out under the influence of an external shear field. The research was carried out using static multiple light scattering (S-MLS) and rheometric measurement techniques coupled with small-angle light scattering (Rheo-SALS). It has been found that the introduction of an external shear field (orthokinetic regime) accelerates the aggregation of chitosan systems. Simultaneously, the rotational measurements can even lead to spontaneous gelation, most likely caused by changes in the conformation of chitosan molecules, their deformation and ordering along the shear field.

Intermetallic PdBi aerogels with improved catalytic performance for the degradation of organic pollutants in water

It is always highly pursued to develop efficient and durable catalysts for catalytic applications. Herein, intermetallic PdBi aerogels with tunable activity were prepared successfully via a surfactant-free spontaneous gelation process. The prepared PdBi aerogels have a three-dimensional high porous structure and plentiful active sites pervaded on the ultrathin interlinked nanowires network. These unique structures, as well as the synergistic effect between Pd and Bi, can accelerate mass and electron transfer, and improve the atom utilization ratio of Pd atoms to promote the catalytic efficiency. As a proof-of-concept application, the optimized Pd2Bi1 aerogels exhibit 4.2 and 6.2 times higher catalytic activity for the reduction of 4-nitrophenol (4-NP) and methylene blue (MB) than those of commercial Pd/C, respectively. With the introduction of non-noble metal of Bi, the cost of the resulted PdBi aerogels can be dropped significantly while the catalytic capability of PdBi aerogel will be improved sharply. This strategy will bring good hints to rationally design fine catalysts for various applications.