NaBH4 Reduction Method Research Articles

Locking the Atomic Ni Leaching on Ordered PtNi Nanostructure for Long-Term Hydrogen Production

To advance the practical performance and durability of alkaline electrolyte membrane water electrolyzers (AEMWE), addressing the sluggish kinetics compared to acidic conditions is imperative in developing highly active and durable electrocatalysts. For mitigating the issues of recession leading to lower catalytic activity, short-term durability, and reduced cost-effectiveness associated with conventional Pt-based electrocatalysts, incorporating transition metals is an effective strategy by modifying the metal-metal (M-M) lattice and electronic structure. Among the transition metals for alloying with Pt, especially, Ni is a suitable secondary atom because it is well-known to promote water dissociation and has a proper ∆GH* value close to Pt. However, the Ni atom undergoes a thermodynamic transformation into the Ni(OH)2, leading to dissolution or leaching, and is randomly redistributed during the hydrogen evolution reaction (HER) in alkaline conditions. To address these drawbacks associated with conventional alloy catalysts, there is growing interest in ordered intermetallic nanostructures, which exhibit unique and locally specific geometrical properties. The intermetallic nanostructure could be an effective remedy due to its high chemical and structural stability, attributed to a strong d-d orbital hybridization with an atomically ordered state.In our study, intermetallic PtNi nanostructures are introduced to intrinsically expedite catalytic activity and prolonged durability through the combinational approaches of both computation and experiments. Specifically, the degradation mechanism of electrocatalysts for hydrogen evolution reaction (HER) in alkaline conditions is still questionable despite numerous related research works to enhance catalytic activity and durability. To unlock the degradation mechanism and demonstrate the robust durability of intermetallic-nanostructured HER electrocatalyst, the dissolution potential on the surfaces is theoretically predicted by density functional theory (DFT) calculations. Intermetallic PtNi/C shows higher dissolution potential on overall surfaces such as (111), (110), and (100), indicating more energy requirement for leaching Ni atoms compared to randomly alloyed PtNi/C. Furthermore, theoretical catalytic activity is analyzed using Gibbs free energy diagrams and electronic structure calculations based on density of states (DOS) and Crystal Orbital Hamiltonian Population (COHP) from DFT calculations. These results provide meaningful insights that Ni alloying significantly improves electrocatalysis for the HER compared to conventional Pt catalysts.To experimentally validate these findings, intermetallic PtNi/C are synthesized via the NaBH4 reduction method at a low temperature followed by heat treatment in the N2 atmosphere. Physicochemical analyses including X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and scanning transmission electron microscopy (STEM) with energy-dispersive spectrometry (EDS) confirm atomically controlled structures with lattice strain and electronic structure modifications. To investigate the catalytic performance and the synergist effect of Ni alloying and intermetallic structure for hydrogen production, the electrochemical tests were evaluated in alkaline conditions from half-cell (active area: 0.196 cm2) to practical-scale AEMWE system (active area: 64 cm2). The HER performance was enhanced with lower overpotential at 10 mA cm-2 by alloying Ni atoms into Pt catalysts. According to the results of the accelerated degradation test (ADT), intermetallic PtNi/C well-maintained stability with a lower degradation rate compared to randomly disordered PtNi/C and commercial Pt/C. Notably, a large 3-cell stack cell evaluated the activity and durability for practically industrial feasibility that it showed a negligible degradation rate over a 2000 h operation period.In summary, we successfully unlock the degradation mechanism and synergistic effect of Ni alloying with ordering engineering effect in theory, furthermore, experimentally validate from intrinsic property to practical-scale feasibility. We believe that controlling nanoparticle structure at the atomic scale is an attractive strategy to achieve highly efficient and stable low-PGM electrocatalysts for hydrogen evolution in AEMWE.This work has been supported by the National Research Foundation of Korea (NRF) grant funded by the Ministry of Science and ICT in the Republic of Korea (MSIT) (NRF-2022R1A2C2093090) and was supported by the Ministry of Trade, Industry & Energy (MOTIE, Korea) under the Technology Innovation Program (20019175) supervised by the Korea Evaluation Institute of Industrial Technology(KEIT). Figure 1

3D NiCoW Metallic Compound Nano-Network Structure Catalytic Material for Urea Oxidation.

Urea shows promise as an alternative substrate to water oxidation in electrolyzers, and replacing OER with the Urea Oxidation Reaction (UOR, theoretical potential of 0.37 V vs. RHE) can significantly increase hydrogen production efficiency. Additionally, the decomposition of urea can help reduce environmental pollution. This paper improves the inherent activity of catalytic materials through morphology and electronic modulation by incorporating tungsten (W), which accelerates electron transfer, enhances the electronic structure of neighboring atoms to create a synergistic effect, and regulates the adsorption process of active sites and intermediates. NiCoW catalytic materials with an ultra-thin nanosheet structure were prepared using an ultrasonic-assisted NaBH4 reduction method. The results show that during the OER process, NiCoW catalytic materials have a potential of only 1.53 V at a current density of 10 mA/cm2, while the UOR process under the same conditions requires a lower potential of 1.31 V, demonstrating superior catalytic performance. In a mixed electrolyte of 1 M KOH and 0.5 M urea, overall water splitting also shows excellent performance. Therefore, the designed NiCoW electrocatalyst, with its high catalytic activity, provides valuable insights for enhancing the efficiency of water electrolysis for hydrogen production and holds practical research significance.

Strong Metal–Support Interaction Induces Dual Reaction Sites for Ultrasensitive and Stable NO2 Detection in Extreme Environments

AbstractThe tripartite combination of a high density and stability of surface reaction sites, complemented by the longevity and efficient transfer of interface carriers, along with the effective adsorption and activation of target gas molecules, jointly determines the efficiency of chemiresistors. In this work, the strong metal–support interaction (SMSI) of Pt─Ce3+ is formed by the NaBH4 reduction method and thus prepares metal‐dynamically stable PtNR─CeO2 with Pt─Ce3+ and Pt─Pt reaction sites. The formation of SMSI induces the recombination of the chemical structure of the CeO2 surface causing the localization of electron‐rich Ce3+, which greatly increases the charge concentration at the interface. The experimental findings of the strong interaction of Pt─Ce3+ bonding and the catalytic effect of Pt optimized the adsorption mode of PtNR─CeO2 on target gas, which maintains stable catalytic activity at 20–500 °C and achieving a notable detection response value of 1.43 for 20 ppb NO2. This work offers fresh insights into designing stable oxide chemiresistors with efficiency and stability by customizing reaction sites at the atomic level.

Application of ANN and RSM for Rhodamine B and Safranine-O Decolorization on Zinc-Carbon Battery Waste Derived Ag/CoFe-LDH/rGO Catalyst.

The present work is first aimed at recovering graphite from carbon rods of waste zinc-carbon (Zn-C) batteries for applications such as wastewater treatment, in order to contribute to the development of a sustainable environment. Then, a composite material, cobalt-iron layered double hydroxide combination with reduced graphene oxide, and with subsequent Ag nanoparticles deposition via NaBH4 reduction method (Ag/CoFe-LDH/rGO) was prepared for the catalytic activity of Rhodamine B (RhB) and Safranine-O (SO) as model contaminants from aquatic media. The catalytic activity of RhB and SO by Ag/CoFe-LDH/rGO in the presence of NaBH4 was studied to model and optimize the process parameters (NaBH4 amount, reaction time, initial dye concentration (Co), and catalyst dosage) via central composite design (CCD)-response surface methodology (RSM). Also, an artificial neural network (ANN) model was developed to estimate the catalytic activity of each dye using an RSM data set. The catalytic activities of 99.54% and 99.96% were obtained for RhB and SO dyes, respectively, under the optimal conditions: NaBH4 amount 12.32 mM, reaction time 3.19 min, Co 33.46 mg/L, and catalyst dosage 1.24 mg/mL for RhB dye; NaBH4 amount 16.76 mM, reaction time 3.06 min, Co 15.10 mg/L, and catalyst dosage 1.46 mg/mL for SO dye. The optimum conditions of process parameters by ANN with gray wolf optimizer (GWO) were in good agreement with the points determined the RSM-CCD. These results demonstrate that RSM and ANN approaches can be applied practically and efficiently to maximize the catalytic activity of RhB and SO by Ag/CoFe-LDH/rGO in the existence of NaBH4. On the other hand, from the kinetic and thermodynamic studies, the positive activation enthalpy, ΔH# and the negative activation entropy, ΔS# values for each dye demonstrated that the catalytic performance was endothermic and less random at the solid/liquid interface.

Insight into the degradation mechanism of mixed VOCs oxidation over Pd/UiO-66(Ce) catalysts: Combination of operando spectroscopy and theoretical calculation

Herein, Pd/UiO-66(Ce) catalysts were successfully synthesized by N2H4, H2, and NaBH4 reduction methods with UiO-66(Ce) as support. The best catalyst was selected via utilizing o-xylene as the probe molecule, and its degradation performance of mixed VOCs was further investigated. It was found that the reduction methods greatly influenced the size of Pd nanoparticles, the state of surface Pd, and the support structure in the catalysts, which in turn affected their catalytic performance. Among them, Pd/UiO-66(Ce)-Na exhibited the best o-xylene degradation activity (T90 = 192 °C) due to its smaller average Pd particle size (Pd Average = 2.93 nm) and higher surface Pd0 content (Pd0/Pdtotal = 0.79). The performance and interaction of Pd/UiO-66(Ce)-Na catalyst for degradation of mixed VOCs (o-xylene and toluene/benzene) were investigated by DFT adsorption energy calculation, in situ DRIFTS and GC–MS. Results suggested that the single adsorption energy of o-xylene was −1.20 eV, while in the system with toluene/benzene, the adsorption energy decreased to −0.78 and −0.6 eV, respectively. This showed the competitive adsorption effect between benzene and o-xylene was stronger than that between benzene and o-xylene. Finally, combined with in situ DRIFTS and GC–MS, the degradation path of mixed components was analyzed and studied systematically, and the mechanism of intermolecular interaction of benzene in the degradation process of mixed components was further revealed.

Morphology-dependent support effect of PdCu/alpha-Fe2O3 catalysts on Suzuki-Miyaura cross-coupling reaction

The palladium-catalyzed Suzuki-Miyaura cross-coupling (SMC) reaction has received worldwide attention as a powerful and convenient synthetic tool for the formation of biaryl compounds. However, these reactions are highly dependent on the activity and stable of catalysts. Herein, the support morphology-dependent catalytic performance of SMC reactions was investigated. The truncated hexagonal bipyramid (α-Fe2O3-O) and rod-shaped morphologies of alpha-Fe2O3 (α-Fe2O3-R) were used as support to prepare PdCu nanoparticles (NPs) catalysts by NaBH4 reduction method. For PdCu/α-Fe2O3-R catalysts, the smaller size of PdCu NPs and more low coordination Pd sites leading to its superior catalytic performance for SMC reactions. Furthermore, it can be easily recycled through centrifugation and reused several times without obvious loss on its catalytic performance. Identical location transmission electron microscopy method was used to investigate the structural evolution of PdCu/α-Fe2O3-R catalysts. The results found that its structure almost unchanged during the catalytic reaction.

Catalytic Oxidation of Toluene over Pt/CeO2 Catalysts: A Double-Edged Sword Effect of Strong Metal-Support Interaction.

Strong metal-support interaction (SMSI), which has drawn widespread attention in heterogeneous catalysis, is thought to significantly affect the catalytic performance for volatile organic chemical (VOC) abatement. In the present study, strong interactions between platinum and ceria are constructed by modulating the oxygen vacancy concentration of CeO2 through a NaBH4 reduction method. For a catalyst with higher content of oxygen vacancy, more electrons would transfer from ceria to Pt, which is attributed to the stronger effect of SMSI. The obtained electron-richer Pt sites exhibit higher ability for toluene activation, contributing to better performance for toluene oxidation. On the other hand, the stronger metal-support interaction would facilitate CeOx species migrating to the Pt nanoparticle surface and forming an encapsulated structure. Smaller Pt dispersion leads to fewer sites for toluene adsorption and activation, which is to the disadvantage of the reaction. Therefore, taking the negative and positive effects together, the Pt/CeO2-0.5 catalyst has the highest catalytic performance for toluene abatement. Our study provides new insights into strong metal-support interaction on toluene oxidation and contributes to designing noble metal catalysts for VOC abatement.

Selective hydrogenolysis of 5-hydroxymethylfurfural to 2,5-dimethylfuran with high yield over bimetallic Ru-Co/AC catalysts.

Catalytic hydrogenolysis of 5-hydroxymethylfurfural (HMF) to 2,5-dimethylfuran (DMF) has become a hot topic in the bioenergy field in recent years. It remains a challenge to mediate the activation/hydrogenation/hydrogenolysis of C-O and C[double bond, length as m-dash]O bonds of HMF at high temperatures. Herein, bimetallic Ru-Co/AC catalysts were prepared by the "two-step" reduction method and were used to catalyze the hydrogenolysis of HMF to DMF. The effects of different reduction methods, Ru/Co ratios, and Ru loading on the catalytic performances of the Ru-Co/AC catalysts were investigated, and the physicochemical properties of the catalysts were characterized by TEM, XPS, H2-TPR, etc. It was found that the catalysts reduced by the "two-step" reduction method exhibited better catalytic activities than those fabricated by a single H2 or NaBH4 reduction method. The introduction of Co metals promoted the dispersion of Ru nanoparticles (NPs) on AC and the transfer of electrons from Co to Ru, thereby improving the catalytic activity. An excellent yield of DMF up to 97.9% and 98.7% conversion of HMF were achieved in a short time (1.5 h) under the optimal conditions (200 °C, 1 MPa). Furthermore, the possible reaction pathway for the hydrogenolysis of HMF to DMF over 5%Ru-1%Co/AC catalyst is also discussed. The work shows that the Ru-Co/AC catalysts have great potentials for the conversion of HMF into liquid fuel DMF.

Uncalcined TS-1 supported Au catalyst via NaBH4 reduction method for propylene epoxidation: Insights into the H2 pretreatment effect on catalytic performance

Stable and efficient Au-supported titanium silicalite-1 (TS-1) catalysts are essential for the direct epoxidation of propylene (DEP) using O2 and H2. But the deposition-precipitation method for Au/TS-1 contains low Au capture efficiency and rapid deactivation rate. Herein, Au/TS-1-B (uncalcined TS-1) catalysts were synthesized through a NaBH4 reduction method. The impact of H2-thermal-pretreatment on DEP activities was studied. H2-pretreatment can enhance propylene oxide selectivity, shorten activation time and reduce deactivation rate of catalyst. Organic-templates on the surface of TS-1-B and stabilizers coated on Au-nanoparticles can be partially removed under H2-treatment, thus exposing more active sites for Au and Ti and facilitating their interactions. Furthermore, more porous structures with reduced acid sites and enhanced surface hydrophobicity of pretreated catalyst can promote DEP reaction. Solid stability in TS-1-B, high Au utilization resulting from the reduction method, and favorable modifications through H2-thermal treatment contribute to the exploration of more robust DEP catalyst performance.

Response surface methodology optimization of electrode modification parameters toward hydrazine electrooxidation on Pd/MWCNT/GCE

In this study, MWCNT supported Pd (Pd/MWCNT) was synthesized by NaBH4 reduction method as catalyst for hydrazine electrooxidation reaction (HEOR). Characterization methods namely inductively coupled plasma mass spectrometry (ICP-MS), elemental mapping, and scanning electron microscopy with energy dispersive X-ray (SEM-EDX) were used to analyze the surface morphology and metal composition of the catalysts. The Pd/MWCNT catalyst's average particle size is estimated to be 6.35 nm based on SEM images. Glassy carbon electrode (GCE) modification parameters namely the amount of catalyst ink transferred to the GCE surface (Vs), ultrasonication time of the catalyst ink (tu), and the drying time of the Pd/MWCNT/GCE (td) were optimized by using response surface methodology as 4.92 μL, 1 min and 19.52 min, respectively. Experimental specific activity value for HEOR was obtained as 7.13 mA cm-2 with 2.59% deviation under optimum conditions. Optimization of electrode preparation conditions is an inexpensive and facile method that could be used to improve the performance of anode catalysts for fuel cells.

Synergistic Integration of Zr-MOF (UiO-66) and Bi Electrocatalysts for Enhanced CO2 Conversion to Formate

The utilization of renewable energy-driven CO2 conversion technology has garnered considerable attention as a potential remedy for both the energy crisis and climate change. Among various methods, the electrocatalytic CO2 reduction reaction (CO2RR) has received particular focus due to its mild reaction conditions and its ability to produce various valuable products. Specifically, formic acid holds great promise for CO2 electrolysis due to its potential for energy storage and transportation, as well as its commercial viability as indicated by techno-economic assessments. Bi, In, and Sn are several metal catalysts that have been reported for formic acid production, with Bi catalysts demonstrating favorable properties in terms of both cost-effectiveness and selective production of formic acid. However, despite efforts to enhance the intrinsic catalytic activity of Bi through methods such as nanostructuring and alloying, it has yet to achieve the desired level of performance. In light of recent findings by Nam et al. on the ability of a metal-organic framework (MOF) to regulate reaction intermediates for Ag catalyst, resulting in higher CO production, we draw inspiration from MOF's versatility and demonstrate the successful coupling of Bi with UiO-66, a Zr-MOF, to achieve higher CO2 reduction rates and thus increase formic acid production [1]. We synthesized MOF materials, UiO-66 and NH2-functionalized UiO-66 (UiO-66-NH2), and deposited Bi catalysts on the MOF structures using the NaBH4 reduction method, resulting in Bi/UiO-66 and Bi/UiO-66-NH2 samples. To compare the catalytic activity, we also synthesized Bi particle samples using the same method (Bi). Prior to CO2 reduction examination, all electrocatalysts were pre-treated in a 1.0 M KOH solution for 5 minutes, and then CO2 electrolysis was performed in a flow-cell reactor. Among the synthesized samples, Bi/UiO-66 demonstrated excellent CO2 reduction properties, exhibiting about 5 times higher current density (-220 mA/cm2) at an applied potential of -0.7 V vs. the reversible hydrogen electrode (RHE) than Bi alone (-44 mA/cm2), despite the identical electrochemically active surface area (ECSA) for both samples. On the other hand, Bi/UiO-66-NH2 showed an almost identical ECSA-normalized current density compared to Bi/UiO-66, indicating the negligible effect of NH2 functionalization on UiO-66 for CO2RR. Nevertheless, it is evident that the utilization of Zr-MOF (UiO-66) is beneficial in increasing the CO2 conversion rate of metallic Bi catalyst. To comprehend the reason behind the superior catalytic activity exhibited by the Bi/UiO-66 sample, we conducted various characterizations, such as SEM, TEM, FTIR, Raman, and XPS. Our results revealed that the structural evolution of UiO-66 occurs by the formation of carbonate-coordinated Zr-hydroxide during CO2 electrolysis, contributing to the high CO2 reduction current density. Moreover, the disappearance of the carbonate-relevant peak in the C 1s from XPS analysis after the decline in catalytic activity suggests that the carbonate species formed at Zr-MOF site, which is the captured form of CO2 molecules, play a crucial role in efficient CO2 capture and conversion. These findings suggest that Zr-MOF can be used for CO2 capture and conversion with high efficiency.[1] Nam et al., J. Am. Chem. Soc. 2020, 142, 51, 21513–21521.

Sulfur vacancies reinforced cobalt molybdenum sulfide nanosheets integrated cathode for high energy density hybrid supercapacitors

Rational design and construction of bimetallic sulfide materials integrated cathode with well-defined hierarchical nanoarchitectures plays a vital role in boosting the electrochemical performance of hybrid supercapacitors (HSCs). Herein, sulfur vacancies reinforced cobalt molybdenum sulfide nanosheets (Vs-CMS) integrated cathodes are prepared by hydrothermal and NaBH4 reduction methods. The introduction of sulfur vacancies in CMS not only contributes to more active sites for faradic redox reactions but also accelerates electron and ion transmission. Benefiting from the synergistic effects of well-defined hierarchical nanoarchitecture and sulfur vacancies, the optimal Vs-CMS integrated cathode delivers a high areal capacity of 0.56 mAh cm−2 at 1 mA cm−2, good rate performance of 0.34 mAh cm−2 at 30 mA cm−2, and excellent cycling stability with 96.7% capacity retention after 10,000 cycles. Furthermore, capacitive-type porous framework activated carbon (PFAC) anodes are used to couple with the optimal Vs-CMS cathodes for assembling HSCs. The as-obtained PFAC anodes possess a high specific capacitance of 112.1 F g− 1 at 0.25 A g− 1, high rate capability of 46.3 F g− 1 at 10 A g− 1, and good cycling stability of 95.5% capacitance retention after 10,000 cycles. The as-assembled HSCs deliver maximum energy density of 73.2 Wh kg−1 and power density of 3014.7 W kg−1, and prominent cyclic stability of 93.3% capacity retention after 10,000 cycles.

Remarkably enhanced hydrogen evolution of g-C3N4 nanosheet under simulated sunlight via AgPt alloy co-catalyst with low amount of Pt

The development of low-cost co-catalysts matched with proper photocatalysts to enhance the photocatalytic hydrogen evolution performance is highly demanded. Herein, the AgPt bimetallic alloy nanoparticles with small amounts of Pt were decorated on g-C3N4 nanosheets (AP-CN) via the NaBH4 reduction method, which were further used as catalysts towards photocatalytic hydrogen evolution from water under AM1.5 irradiation. Compared to mono-metallic co-catalysts, bimetallic AgPt alloy nanoparticles exhibited excellent co-catalytic performance. The optimum AP-CN photocatalyst with 0.5 wt% Pt exhibited photocatalytic hydrogen evolution rate of 3507.89 μmol g−1·h−1, which even surpassed that of the commonly-used photocatalyst 1.0 wt% Pt in-situ photo-deposited on g-C3N4. Meanwhile, the AP-CN showed excellent photocatalytic activity and durability after four experimental cycles. The enhanced activity and stability could be attributed to the synergistic effect between plasmonic metal Ag and Pt, which promoted the transfer and separation of photoinduced charge carriers. Besides, the theoretical results based on DFT calculation also verified that AgPt alloys have better performance of desorbing hydrogen and adsorbing H atoms. This work provides a feasible idea for the development of inexpensive and efficient bimetallic co-catalysts for photocatalytic hydrogen production through water splitting.

Gold nanoparticles supported on modified dumbbell shaped nanorod cluster CuBi2O4 for the selective oxidation of benzyl alcohol under visible light

Dumbbell-shaped nanorod cluster CuBi2O4 was fabricated by a hydrothermal method, and a variety of × wt% Au/CuBi2O4 (x = 1, 2, 3, 4, 5, 6) were prepared by NaBH4 reduction method. By using XRD, XPS, SEM, TEM, UV–vis DRS and BET, it was demonstrated that the catalysts were successfully synthesized. Density functional theory (DFT) was used to study the band structure, density of states (DOS) and differential charge density of catalysts. DFT results showed that the energy gap of CBO and Au/CBO was 1.74 eV and 1.59 eV, respectively. Because of Au loading, the recombination of e- and h+ pairs is significantly inhibited because h+ has a greater effective mass in the VB and its photocatalytic selective oxidation of benzyl alcohol is enhanced. Au was found to have an important effect on the enhancement of the photocatalytic activity of the catalyst. Au/CuBi2O4 composites have dramatically a higher degree of separation of the photogenerated carriers than that of pristine CuBi2O4 according to PL and EIS. By optimizing the reaction conditions and comparing different catalysts, GC and GC–MS revealed that 4 wt% Au/CuBi2O4 was the optimum catalyst. Under green mild conditions, the conversion of benzyl alcohol to benzaldehyde can achieve 88.9% with a selectivity of 99%. Moreover, the catalyst was stable by the reuse experiment. A plausible mechanism for the selective oxidation of benzyl alcohol was proposed based on the DFT and experimental results.

Mesoporous black TiO2 hollow shells with controlled cavity size for enhanced visible light photocatalysis.

Black TiO2 formed by introducing lattice disorder into pristine TiO2 has a narrowed band gap and suppresses the recombination of charge carriers. This provides a potential strategy for visible light photocatalysis. However, the microstructural design of black TiO2 for a higher optimization of visible light is still in high demand. In this work, we proposed the preparation of black TiO2 hollow shells with controllable cavity diameters using silica spheres as templates for the cavities and the NaBH4 reduction method. The decreased cavity size resulted in a hollow shell with an enhanced visible-light absorption and improved photocatalytic performance. Moreover, we demonstrated that this cavity can be combined with gold nanoparticles (AuNPs) to form AuNPs@black TiO2 yolk-shells. The AuNPs provided additional visible light absorption and promoted the separation of photogenerated carriers in the yolk-shell structures. This further improved the photocatalysis, the degradation rate of Cr(VI) can reach 0.066 min-1. Our work evaluated the effect of the cavity size on the photocatalytic performance of hollow and yolk-shell structures and provided concepts for the further enhancement of visible-light photocatalysis.

Supported PbHfCd electrocatalysts over carbon-hydroxyapatite composite fabricated by precipitation and NaBH4 reduction methods for glucose electrooxidation

Supported PbHfCd electrocatalysts over carbon-hydroxyapatite composite fabricated by precipitation and NaBH4 reduction methods for glucose electrooxidation

A General Synthesis of Crystal Phase Controllable Aerogels for Efficient Hydrogen Evolution.

Amorphous/crystalline (a/c) hetero-phase structures are considered as a class of efficient electrocatalysts for hydrogen evolution reaction (HER), but it remains a substantial challenge to obtain the specific phase by phase-selective synthesis. In this work, a general route for the preparation of various heterogeneous aerogels (RuB, PtB, PdB, and RhB) consisting of amorphous and crystalline phases is presented through a controlled NaBH4 reduction method. The prepared a/c-RuB aerogel exhibits better HER performance due to their desirable compositional and structural advantages such as more exposed active sites, optimized electronic structure, and interfacial synergistic effects. It requires only a low overpotential of 39mV to reach a density of 10mA cm-2 and also exhibits excellent stability. This work provides a new phase-selective synthesis strategy for the design and development of advanced hetero-phase electrocatalysts.

Self-Supported 3D PtPdCu Nanowires Networks for Superior Glucose Electro-Oxidation Performance.

The development of non-enzymatic and highly active electrocatalysts for glucose oxidation with excellent durability for blood glucose sensors has aroused widespread concern. In this work, we report a fast, simple, and low-cost NaBH4 reduction method for preparing ultrafine ternary PtPdCu alloy nanowires (NWs) with a 3D network nanostructure. The PtPdCu NWs catalyst presents significant efficiency for glucose oxidation-reduction (GOR), reaching an oxidative peak-specific activity of 0.69 mA/cm2, 2.6 times that of the Pt/C catalyst (0.27 mA/cm2). Further reaction mechanism investigations show that the NWs have better conductivity and smaller electron transfer resistance. Density functional theory (DFT) calculations reveal that the alloying effect of PtPdCu could effectively enhance the adsorption energy of glucose and reduce the activation energy of GOR. The obtained NWs also show excellent stability over 3600 s through a chronoamperometry test. These self-supported ultrafine PtPdCu NWs with 3D networks provide a new functional material for building blood glucose sensors and direct glucose fuel cells.

Regulating electronic metal-support interaction by synthetic methods to enhance the toluene degradation over Pt/Co3O4 catalysts

The synthesis method of precious metal catalysts would affect the electronic metal-support interaction (EMSI) of catalysts, which further affected the catalytic activity. In this paper, Co3O4 was obtained as support by the pyrolysis of ZIF-67 as a template sacrificial agent, and Pt species were loaded by three different reduction methods. Among them, the catalyst produced by the NaBH4 reduction method possessed the best activity with T90 of 168 °C. Through a series of characterization and experiments, it was found that the EMSI of the catalyst was optimized by this synthesis method, which led to electron transfer among Pt species and Co3O4. The catalysts also exhibited excellent water resistance, stability, and recycling performance. The possible degradation mechanism of toluene was also revealed by in situ DRIFTS and GC–MS. This paper provided ideas for the construction of catalysts and a theoretical reference for the relevant verification of EMSI.

Fabrication and characterization of poly(tannic acid) coated magnetic clay decorated with cobalt nanoparticles for NaBH4 hydrolysis: RSM-CCD based modeling and optimization

Hydrogen generation from sodium borohydride (NaBH4) hydrolysis in the presence of metal catalysts is a frequently used and encouraging method for hydrogen storage. Metal nanoparticle-supported catalysts are better recyclability and dispersion than unsupported metal catalysts. In this study, the synthesis and characterization of a polymer-supported catalyst for hydrogen generation using NaBH4 have been investigated. For the synthesis of polymeric material, first of all, kaolin (KLN) clay has been magnetically rendered by using the co-precipitation method (Fe3O4@KLN) and then coated with poly tannic acid (PTA@Fe3O4@KLN). Then, the catalyst loaded with cobalt (Co) nanoparticles have been obtained with the NaBH4 reduction method (Co@PTA@Fe3O4@KLN). The surface morphology and structural properties of the prepared catalysts have been determined using methods such as scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FT-IR), X-ray powder diffraction (XRD), X-ray photoelectron spectroscopy (XPS), inductively coupled plasma mass spectrometry (ICP-MS) and vibrating sample magnetometer (VSM). The optimization of the most important variables (NaBH4 amount, NaOH amount, catalyst amount, and metal loading rate) affecting the hydrolysis of NaBH4 using the synthesized polymeric catalysts was carried out using response surface methodology (RSM). Depending on the evaluated parameters, the desired response was determined to be hydrogen production rate (HGR, mL/g min). HGR was 1540.4 mL/gcat. min. in the presence of the Co@PTA@Fe3O4@KLN at optimum points obtained via RSM (NaBH4 amount 0.34 M, NaOH amount 7.9 wt%, catalyst amount 3.84 mg/mL, and Co loading rate 6.1%). The reusability performance of the catalyst used in hydrolysis of NaBH4 was investigated under optimum conditions. It was concluded that the catalyst is quite stable.