Co-reduction Method Research Articles

Pd nanoparticles on DUT-67-PZDC-derived N-doped carbon for efficient H2 generation from formic acid dehydrogenation

It is important to develop heterogeneous catalysts with high efficiency and stability to catalyze formic acid (FA, HCOOH) dehydrogenation. Herein, through pyrolysis of DUT-67-PZDC and etching in a hydrofluoric acid (HF) solution, the HF-etched N-doped carbon (HNDC) carrier was obtained. Palladium nanoparticles (Pd NPs), with an average particle size of 3.0 nm, were prepared on the HNDC support using a simple chemical co-reduction method. The optimized Pd/HNDC catalyst demonstrates excellent catalytic activity, the initial turnover frequency (TOF) value is 6001 h−1 at 50 °C with the incorporation of sodium formate (SF) as an additive, and the FA conversion and hydrogen (H2) selectivity could be up to 100%, which is comparable to the majority of MOF-derived heterogeneous catalysts published to date. Additionally, the Pd/HNDC can maintain good stability in five consecutive FA dehydrogenation runs with only a slight decrease. Such remarkable catalytic performance of Pd/HNDC is mainly ascribed to the unique structure of HNDC support with high surface area and hierarchical pore characteristic, the strong synergistic interaction between Pd NPs and the N sites on HNDC, as well as the ultrasmall size and high dispersion of Pd NPs as the catalytic active site. This work offers an efficient method for assembling highly active catalysts for FA dehydrogenation.

Bimetallic PdCu anchored to 3D flower-like carbon material for portable and efficient detection of glyphosate

Glyphosate (Gly), as a widely used broad-spectrum herbicide, may lead to soil and water pollution due to its persistence in the environment. Herein, the co-reduction method was employed to anchor bimetallic PdCu onto the Ni and nitrogen-doped 3D Flower-like Carbon Materials (Ni@NC), creating a composite material (PdCu/Ni@NC) with high specific surface area and good catalytic performance. This composite was used to modify screen-printed electrodes (SPE) to develop a portable and efficient Gly detection platform. In the presence of Cl⁻, the copper active sites convert to CuCl, achieving signal amplification. Upon the addition of Gly, a competitive reaction between Cu and Gly converts CuCl into a Cu-Gly complex, resulting in a sharp decrease in the electrochemical signal. This signal drop is used to detect Gly. The bimetallic PdCu nanoparticles (NPs) endowed the sensing platform with better stability and electrochemical performance due to their synergistic effect, and their stability was simply verified by Density functional theory (DFT). The sensor demonstrates a linear detection range spanning from 1 × 10⁻¹ ³ to 1 × 10⁻⁵ M, with a limit of detection (LOD) of 3.72 × 10⁻¹ ⁴ M. The sensor demonstrated a recovery rate of 95.9 % to 104.5 % in actual samples such as water and soil, indicating its potential for practical application.

Enhanced Electrocatalytic Performance of the FePt/PPy-C Composite toward Methanol Oxidation.

A novel FePt/PPy-C composite nanomaterial has been designed and investigated as a methanol oxidation reaction (MOR) electrocatalyst. The FePt nanoparticles with an average diameter of about 3 nm have been prepared by the co-reduction method and then loaded onto the PPy-C composite support. The electrocatalytic performance is affected by the composition of the FePt nanoparticles. The experimental results indicated that the Fe1.5Pt1/PPy-C catalyst exhibited excellent catalytic activity and stability for MOR, with mass activity and specific activity of 1.76 A mgPt-1 and 2.71 mA cm-2, respectively, which are 5.18 and 4.60 times higher than that of the commercial Pt/C catalyst. Density functional theory (DFT) has been employed to simulate the electrical structures of catalyst supports, and the mechanism of the methanol oxidation process has been further analyzed. The heterojunctions of the PPy-C interface could accelerate the electron migration from the electrocatalytic center to the electrodes. The possibility of methanol oxidation has been improved effectively, which can be confirmed by the d-band center and CO adsorption energy on FePt nanoparticles in the DFT calculation results.

Ultrasmall Pd nanoparticles supported on a metal–organic framework DUT-67-PZDC for enhanced formic acid dehydrogenation

The highly dispersed ultrasmall palladium nanoparticles (Pd NPs) (1.7 nm) were successfully immobilized on a N-containing metal–organic framework (MOF, DUT-67-PZDC) using a co-reduction method, and it is used as an excellent catalyst for formic acid dehydrogenation (FAD). The optimized catalyst Pd/DUT-67-PZDC(10, 10 wt% Pd loading) shows 100% hydrogen (H2) selectivity and formic acid (FA) conversion at 60 °C, and the commendable initial turnover frequency (TOF) values of 2572 h−1 with the sodium formate (SF) as an additive and 1059 h−1 even without SF, which is better than most reported MOF supported Pd monometallic heterogeneous catalysts. The activation energy (Ea) of FAD is 43.2 KJ/mol, which is lower than most heterogeneous catalysts. In addition, the optimized catalyst Pd/DUT-67-PZDC(10) maintained good stability over five consecutive runs, demonstrating only minimal decline in catalytic activity. The outstanding catalytic performance could be ascribed to the synergistic corporations of the unique structure of DUT-67-PZDC carrier with hierarchical pore characteristic, the metal-support interaction (MSI) between the active Pd NPs and DUT-67-PZDC, the highly dispersed Pd NPs with ultrafine size serve as the catalytic active site, as well as the N sites on the support could act as the proton buffers. This work provides a new paradigm for the efficient H2 production of FAD by constructing highly active heterogeneous Pd-based catalysts using MOF supports.

Octahedral Nanocrystals of Ru-Doped PtFeNiCuW/CNTs High-Entropy Alloy: High Performance Toward pH-Universal Hydrogen Evolution Reaction.

Integrating high-entropy philosophy and nanocrystal-specific orientation into a single catalyst represents a promising strategy in development of high-performance catalysts. Nonetheless, shape-controlled synthesis of high-entropy alloy (HEA) nanocrystals is challenging owing to the distinct redox potentials and growth dynamics of metal elements. Herein, a one-pot co-reduction method is developed to fabricate ruthenium (Ru)-doped PtFeNiCuW octahedral HEA nanocrystals onto carbon nanotubes (Ru-PtFeNiCuW/CNTs). It is demonstrated that Ru dopants and W(CO)6 promote the concurrent reduction and growth of other metal precursors to obtain higher yield and larger size of HEA nanocrystals, despite low Ru content in Ru-PtFeNiCuW/CNTs. As an electrocatalyst toward hydrogen evolution reaction (HER), Ru-PtFeNiCuW/CNTs exhibits low overpotentials of 9, 16, and 34mV at a current density of 10mA cm-2 and Tafel slopes of 19.2, 27.9, and 23.1mV dec-1 in acidic, alkaline, and neutral electrolytes, respectively. As a cathodic catalyst, Ru-PtFeNiCuW/CNTs operates for up to 1500 and 1200 h in acidic and alkaline electrolyte, respectively, at a current density of 50mA cm-2 in a two-electrode system for full water splitting. Theoretical calculations reveal accelerated kinetics of H2O dissociation on W sites and *H desorption on hollow Cu-Cu-Cu and Cu-Cu-Pt sites.

Bimetallic PtPd functionalized In2O3 nanoparticles for TEA sensing: A combined experimental and theoretical study

Bimetallic PtPd nanostructures were synthesized via a facile one-step coreduction method at room temperature and loaded on the In2O3 nanoparticles (NPs) through self-assemblies. Among the PtPd-functionalized In2O3 NPs with different PtPd alloy compositions, the sample with the Pt/Pd molar ratio of 3.0 exhibits the highest response value of 232.7 in the detection of 100 ppm triethylamine at 130 °C and a detection threshold as low as 5 ppm. Besides, the optimal working temperature was reduced by 30 °C and the selectivity coefficient under the interference of ammonia and some common VOCs elevated from 2.54 to 4.85 compared with the pristine counterpart. Eventually, the sensitization mechanism referring to the pristine In2O3 and monometal-functionalized In2O3 is explained by oxygen vacancy, the metal/metal oxide-semiconductor junctions and the synergistic catalytic effect of the PtPd nanostructure with the help of density functional theory simulations.

Controlling the composition and nanostructure of Au@Ag–Pt core@multi-shell nanoparticles prepared by co-reduction method

Three types of Au@Ag–Pt core@multi-shell nanoparticles (NPs) were synthesized via a co-reduction reaction from a galvanic replacement reaction (GRR) and a reducing agent, with different feeding ratios of Ag or Pt precursors. The morphology of the core-shell NPs showed a thin multi-shell with a mixture of Ag, void, and Pt granules, and their microstructure was investigated by scanning transmission electron microscopy. The effect of the Ag or Pt precursor feeding ratios on the competition of the two reduction reactions, and the subsequent impact on the nanostructure of Ag-void-Pt multi-shell were discussed. In the case of the sample with a reduced Ag precursor feeding ratio, the thickness of the Ag layer decreased significantly. The oxidation resistance of the Ag layer was improved due to the charge-transfer effect from Au to Ag, which suppressed galvanic replacement, and the reaction by the reducing agent was dominant. In the case of the sample with a reduced Pt precursor feeding ratio, the number of Pt granules was found to decrease while the volume of voids was maintained, suggesting that GRR was the dominant reaction in the co-reduction method. These results provide further insight into the co-reduction reaction mechanism and enable the control of noble trimetallic nanoparticles with complex shells.

Ammonia detection based on Pd/Rh-GaN and recognition of disease markers of nitrogen compounds assistant by deep learning

Bimetallic has received a lot of attention due to its excellent catalytic performance. Herein, bimetallic nanofilms were successfully modified on GaN epitaxial wafer by a co-reduction method in polyol solution, and different concentrations of Pd/Rh-GaN were obtained. Meanwhile, the morphology and structure of Pd/Rh-GaN were subjected to a series of measurements, and the gas sensors modified with bimetallic modification were also studied for gas sensitivity. The results of the gas-sensitive properties show that the Pd/Rh-GaN-0.25 sensor has outstanding gas-sensing performance with the highest sensitivity, the lowest limit of detection, and the fastest response/recovery time. In addition, we extended other bimetallic nanoparticles to Pd/Ru and Pt/Ru, and deep learning was combined with the sensor array to recognize three markers of nitrogen compounds (NH3, NO2, TMA) in Exhaled breath, achieving high precision recognition with up to 96 % accuracy. This work offers a new approach for the design and preparation of gas sensors for early warning of chronic kidney disease.

Laser Irradiation Synthesis of AuPd Alloy with Decreased Alloying Degree for Efficient Ethanol Oxidation Reaction.

The preparation of electrocatalysts with high performance for the ethanol oxidation reaction is vital for the large-scale commercialization of direct ethanol fuel cells. Here, we successfully synthesized a high-performance electrocatalyst of a AuPd alloy with a decreased alloying degree via pulsed laser irradiation in liquids. As indicated by the experimental results, the photochemical effect-induced surficial deposition of Pd atoms, combined with the photothermal effect-induced interdiffusion of Au and Pd atoms, resulted in the formation of AuPd alloys with a decreased alloying degree. Structural characterization reveals that L-AuPd exhibits a lower degree of alloying compared to C-AuPd prepared via the conventional co-reduction method. This distinct structure endows L-AuPd with outstanding catalytic activity and stability in EOR, achieving mass and specific activities as high as 16.01 A mgPd-1 and 20.69 mA cm-2, 9.1 and 5.2 times than that of the commercial Pd/C respectively. Furthermore, L-AuPd retains 90.1% of its initial mass activity after 300 cycles. This work offers guidance for laser-assisted fabrication of efficient Pd-based catalysts in EOR.

Synthesis, characterization, and FDTD simulations of Ag-enriched RGO nanosheets for catalytic reduction of 4-nitrophenol

Reduced graphene oxide-based nanocomposites are eminent materials having diverse applications including environmental remediation. The present work emphasizes the facile one-step co-reduction method for synthesizing silver nanoparticle (Ag NPs) decorated reduced graphene oxide (RGO) for catalytic reduction of 4-nitrophenol. FDTD simulation studies justify the experimental results, and XRD studies confirmed the reduction of graphene oxide and the formation of Ag NPs with reduced graphene oxide (AgRGO) composite. Raman analysis complements the structure, crystallinity, and defects in the fabricated material. XPS analysis verifies the reduction of graphene oxide (GO) into RGO and the decoration of metallic Ag on the surface of RGO. FESEM image showed the decoration of Ag NPs on the surface of RGO. AgRGO exhibited appreciable catalytic performance for reducing 4-nitrophenol in the presence of sodium borohydride compared to GO and RGO.

Insights into the role of ionic surfactants on the morphology of gold and gold@silver nanoparticles

Cyanidin-3, 5-di-O-glycoside (anthocyanin) was extracted from the red rose flower petals in an aqueous media. Anthocyanin was used as reductant to the preparation of gold nanoparticles with cationic and anionic surfactants. UV–visible absorption spectroscope, transmission electron microscope, scanning electron microscope, and energy dispersive X-ray spectroscope were employed to determine absorption bands of anthocyanin, surface Plasmon resonance (SPR) band, and morphology of the gold and gold@silver nanoparticles. Anthocyanin exhibited two absorption peaks at 284 and 518 nm, and one shoulder at 328 nm in the UV–visible spectrum. The intensity of these peaks decreases with time after the addition of HAuCl4. The color and the position of SPR band of gold nanoparticles depend on the concentration of gold salt with and without cetyltrimethylammonium bromide (CTAB), and sodium dodecyl sulfate (SDS). The anionic and cationic head groups of SDS and CTAB micelles have significant impact of the morphology of gold nanoparticles. Seedless co-reduction method was used for the synthesis of gold@silver nanoparticles. TEM images clearly indicate the formation of bimetallic gold@silver core-shell nanoparticles. The antioxidant power of AuNPs and gold@silver nanoparticles were tested in terms of the 2,2-diphenyl-1-picrylhydrazyl (DPPH) free radical scavenging activity as a function of different concentrations of nanoparticles.

Porous hemispherical Au@PdAg catalysts for enhancing ethanol electrooxidation

Direct ethanol fuel cell can convert chemical energy into electric energy directly, and has the advantages of being free from Carnot cycle and being friendly to environment, so it has a broad application prospect. However, the insufficient activity and toxicity resistance of anodic catalysts limit their commercial application, mainly due to the limited adsorption sites and the toxic inactivation of catalysts resulting from the production of toxic intermediates (COads) during the ethanol oxidation reaction (EOR) process. In this study, the Au@PdAg porous hemispherical catalyst assembled by nanotubes was successfully prepared by soft template method and co-reduction method using dioctadecyl dimethyl ammonium chloride (DODAC) as surfactant, and its EOR performance was tested. Au@Pd1.0Ag1.0 has the highest mass current density with a peak value of 4048.8 mAmgPd−1, which is 7.8 times of Pd/C (JM). After 5000 s stability test, the residual current density value is still 863.4 mAmgPd−1. The results showed that the introduction of the oxygenophilic metal Ag was conducive to the formation of OHads and the oxidation of COads. The porous structure of the nanotube assembly facilitates electron transfer and provides more adsorption sites, which makes the catalyst show good electrocatalytic activity and anti-CO poisoning ability.

High-Entropy Alloy PtCuNiCoMn Nanoparticles on rGO for Electrooxidation of Methanol and Formic Acid.

High-entropy alloy (HEA) nanoparticles have attracted great attention due to their excellent electrocatalytic properties. Herein, PtCuNiCoMn HEA nanoparticles supported on reduced graphene oxide (rGO) are synthesized via a solvothermal co-reduction method and are used as an electrocatalyst for the electrooxidation of methanol and formic acid. Owing to the synergistic effect between the component metals, the high-entropy effect, and the sluggish diffusion effect, the PtCuNiCoMn HEA nanoparticles possess significantly improved electrocatalytic activity and stability compared to PtCuNiCo, PtCuNi, PtCu, Pt nanoparticles, and the commercial Pt/C catalyst. The results reveal the unique advantages of HEA nanoparticles in the field of electrocatalysis. The synthesis method is simple and effective, which may be valuable for the preparation of other HEA electrocatalysts.

Unraveling the Synergistic Effects of Oxygen Vacancy and Amorphous Structure on TiO2 for High‐Performance Lithium Storage

The improved electronic conductivity and ion diffusion efficiency of TiO2‐based anode materials have been extensively studied by introducing oxygen vacancies or creating amorphous structure. There has been little exploration of the synergistic effects by combining these two modification strategies into one TiO2‐based matrix. In addition, the structure–activity relationship and energy storage mechanism involved remain to be understood. Herein, a facile one‐step coreduction method is reported to successfully produce the oxygen vacancy‐doped amorphous TiO2 nanoparticles. The oxygen vacancy‐doped amorphous TiO2 anode exhibits significantly enhanced electrochemical activity and high‐rate stability (up to 87 mAh g−1 over 10 000 discharge/charge cycles at a current rate of 100 C). This outstanding electrochemical performance is attributable to the synergistic effects of amorphous structure and oxygen vacancies. Density functional theory calculations reveal the enhanced electronic conductivity and thermodynamically favorable lithium insertion architecture due to the introduction of oxygen vacancy and the construction of the amorphous skeleton. Dynamic analysis indicates that the lithium‐storage mechanism is a hybrid of surface capacitive storage and enhanced diffusion‐controlled ion insertion. This work opens up new pathways in developing novel anode materials for efficient energy storage from the wide spectrum of metal oxides.

Dendritic quinary PtRhMoCoFe high-entropy alloy as a robust immunosensing nanoplatform for ultrasensitive detection of biomarker

Recently, high-entropy alloys have superior physicochemical properties as compared to conventional alloys for their glamorous “cocktail effect”. Nevertheless, they are scarcely applied to electrochemical immunoassays until now. Herein, uniform PtRhMoCoFe high-entropy alloyed nanodendrites (HEANDs) were synthesized by a wet-chemical co-reduction method, where glucose and oleylamine behaved as the co-reducing agents. Then, a series of characterizations were conducted to illustrate the synergistic effect among multiple metals and fascinating structural characteristics of PtRhMoCoFe HEANDs. The obtained high-entropy alloy was adopted to build a electrochemical label-free biosensor for ultrasensitive bioassay of biomarker cTnI. In the optimized analytical system, the resultant sensor exhibited a dynamic linear range of 0.0001–200 ng mL−1 and a low detection limit of 0.0095 pg mL−1 (S/N = 3). Eventually, this sensing platform was further explored in serum samples with satisfied recovery (102.0 %). This research renders some constructive insights for synthesis of high-entropy alloys and their expanded applications in bioassays and bio-devices.

Platinum-group-metal quaternary alloys with lattice defects for enhanced oxygen electrocatalysis.

We propose a facile coreduction method to synthesize a platinum-group-metal quaternary alloy anchored on nitrogen-doped hollow carbon spheres (PtPdRuIr/HCS) by using [MClx]y--1-butyl-3-methylimidazole (M = Pt, Pd, Ru, and Ir) ionic liquid. Owing to the steric hindrance of the imidazolium cations, Pt-group metal atoms of different sizes can be deposited at approximately the same pace for the growth of an alloy with lattice defects. The lattice-distorted PtPdRuIr/HCS exhibits enhanced activity toward oxygen electroreduction when benchmarked against Pt counterparts.

Targeted color design of silver-gold alloy nanoparticles.

This research article focuses on the targeted color design of silver-gold alloy nanoparticles (NPs), employing a multivariate optimization approach. NP synthesis involves interconnected process parameters, making independent variation challenging. Data-based property-process relationships are established to optimize optical properties effectively. We define a color target, employ a green chemical co-reduction method at room temperature and optimize process parameters accordingly. The CIEL*a*b* color space (Commission Internationale de l'Éclairage - International Commission on Illumination) and Euclidean distances facilitate accurate color matching to establish the property-process relationship. Concurrently, theoretical Mie calculations explore the structure-property relationship across particle sizes, concentrations, and molar gold contents. The theoretically optimal structure agrees very well with experimental particle structures at the property-process relationship's optimum. The data-driven property-process relationship provides valuable insights into the formation mechanism of a complex particle system, sheds light on the role of relevant process parameters and allows to evaluate the practically available property space. Model validation beyond the original grid demonstrates its robustness, yielding colors close to the target. Additionally, Design of Experiments (DoE) methods reduce experimental work by threefold with slight accuracy trade-offs. Our novel methodology for targeted color design demonstrates how data-based methods can be utilized alongside structure-property relationships to unravel property-process relationships in the design of complex nanoparticle systems and paves the way for future developments in targeted property design.

Rh0.7Ru0.3-MoOx supported on carbon nanotubes boosts hydrogen generation from hydrazine borane at room temperature

Hydrazine borane (HB, N2H4BH3) is gaining attention as a promising chemical hydrogen storage material due to its impressive hydrogen capacity (15.4 wt%) and stability under normal conditions. However, its dehydrogenation properties have remained unsatisfactory despite numerous efforts. In this study, we have successfully developed rhodium-ruthenium nanoparticles modified with MoOx and supported on carbon nanotubes (Rh0.7Ru0.3-MoOx/CNTS) using a facile co-reduction method. Surprisingly, the Rh0.7Ru0.3-MoOx/CNTS catalyst exhibits outstanding performance, surpassing all previously reported activities for HB dehydrogenation. It demonstrates a high turnover frequency (TOF) value of 4412 h−1 at 303 K, 100 % selective conversion of hydrogen, and excellent stability. Through XPS, TEM, BET, and XRD analysis, we have determined that the exceptional performance of Rh0.7Ru0.3-MoOx/CNTS can be attributed to the synergistic effect of CNTS and MoOx on the catalyst's electronic structure, crystal structure, and particle size. These results provide a solid foundation for the potential application of HB in hydrogen fuel cells.

Self-supported PtPdMnCoFe high-entropy alloy with nanochain-like internetworks for ultrasensitive electrochemical immunoassay of biomarker

High-entropy nanomaterials are regarded as the new research hotspots for their intriguing “cocktail effect”. Herein, self-supported PtPdMnCoFe high-entropy alloy with nanochain-like internetworks (PtPdMnCoFe HEAINN) were synthesized by a one-pot co-reduction method, where newly-generated H2 bubbles served as dynamic template, as identified by a series of characterizations. The high-entropy architecture was certificated effectiveness for reduction of H2O2, which was explored as signal amplifier to develop a novel label-free electrochemical amperometric immunosensor for ultrasensitive determination of biomarker neuron-specific enolase (NSE). In the optimized analytical surroundings, the as-fabricated sensor showed a broad linear range of 0.1 pg mL–1 to 200 ng mL–1 for immunoassay of NSE with a low limit of detection (LOD = 0.0036 pg mL–1, S/N = 3), coupled by its quantification in human serum samples with satisfactory results. This work provides valuable guidance for potential applications of high-entropy alloyed materials in biosensors and immunoanalysis.

Trimetallic CoAuPd alloy nanoparticles confined in mesoporous MIL-101 with low transition energy for enhanced hydrogen generation from formic acid

Developing efficient and low-cost catalysts with excellent hydrogen generation from formic acid (FA) is highly desired but challenging. Herein, a uniform CoAuPd alloy nanoparticles (NPs) were successfully confined into MIL-101 by a surfactant-free co-reduction method. The elevated stability of Co0 in the protected alloy NPs makes its application in FA dehydrogenation successful. Significantly, the resulting Co0.3Au0.35Pd0.35/MIL-101 composites with the lower consumption of noble metals exhibit the 100% hydrogen selectivity, highest activity and excellent stability toward hydrogen generation from FA without any additive at room temperature. Theoretical results reveal that the enhanced hydrogen generation from FA can be ascribed to the synergistic effects between CoAuPd alloy NPs and MIL-101 frameworks with lowest transition energy between LUMO and HOMO and highest adsorption energy of FA, as compared to the bimetallic alloy NPs. Therefore, the present results open up new avenues for developing cost effective and high-performance catalysts for the generation of hydrogen from FA by using porous MOFs as hosts for non-noble metal based NPs.