One-step hydrothermal preparation of bi-functional NiS2/reduced graphene oxide composite electrode material for dye-sensitized solar cells and supercapacitors

To screen out suitable electrode materials and overcome the shortcomings of the existed electrode materials for the application in dye-sensitized solar cells and supercapacitors, NiS₂/reduced graphene oxide (NiS₂/rGO) composite material was prepared by a simple one-step hydrothermal method in this paper and applied in the field of both dye-sensitized solar cells and supercapacitors as electrode material. In an electrolyte of 6 M KOH, the NiS₂/rGO composite material with bilayer capacitance characteristics exhibited a high specific capacitance of 259.20 F g⁻¹ at the current density of 0.6 A g⁻¹, which was significantly higher than that of rGO (188.94 F g⁻¹). Moreover, at a current density of 2 A g⁻¹, the NiS₂/rGO composite material had 92.85% capacitance retention after 2000 cycles. When applied as counter electrode material for the dye-sensitized solar cells, the NiS₂/rGO composite material counter electrode exhibited a satisfactory photoelectric conversion efficiency (η) of 3.16% under standard simulated sunlight (AM 1.5 G), which was significantly higher than that of single rGO counter electrode (improved by 90.40%). The NiS₂/rGO composite electrode material prepared by a simple one-step hydrothermal method is a potential bi-functional composite electrode materials for both dye-sensitized solar cells and supercapacitors.     

All‐carbon hybrids for high performance supercapacitors

A hybrid nanostructure with partially reduced graphene oxide (rGO) and carbon nanofibers (CNFs) was fabricated and used as supercapacitor electrodes. A straightforward, environmentally friendly, and low‐cost microwave‐assisted reduction process was developed for the synthesis of rGO/CNF hybrid structures. The fabricated supercapacitor devices showed a specific capacitance of 95.3 F g^?1 and a superior long‐term cycling stability. A capacitance retention of more than 97% after 11 000 galvanostatic charge discharge cycles was obtained. These and other results reported in this paper indicate that high‐rate, all‐carbon, rGO/CNF hybrid nanostructures are highly promising supercapacitor electrode materials.     

Composite phase change material based on reduced graphene oxide/expanded graphite aerogel with improved thermal properties and shape-stability

Composite phase change materials (PCMs) based on reduced graphene oxide/expanded graphite (rGO/EG) aerogel were prepared by hydrothermal self-assembly and impregnation method. The morphology, chemical structure, thermal properties, and shape-stability of the composite PCMs based on rGO/EG aerogel were examined. The results show that rGO sheets form a three-dimensional (3D) network structure and EG particles are attached to rGO sheets and uniformly interspersed in the aerogel. The oxygen-containing functional groups remaining in rGO/EG aerogel promote heterogeneous crystallization of paraffin, leading to increased latent heat. The 3D thermally conductive pathway provided by rGO/EG aerogel improves the composite PCM's thermal conductivity up to 0.79 W·m⁻¹·K⁻¹, which is about 4 times of that of pure paraffin. The leakage of composite PCMs is remarkably improved at very high percentage of paraffin. Simulative light-thermal experiments reveal that the composite PCMs have the ability of conversion and storage of light-thermal energy. In short, 3D network structure of rGO, with the aid of EG, endows the composite PCMs with improved thermal properties, good shape-stability, and light-thermal storage performance.     

A hybrid PEMFC/supercapacitor device with high energy and power densities based on reduced graphene oxide/Nafion/Pt electrode

Proton exchange membrane fuel cells (PEMFCs) possess high energy and low power densities, while supercapacitors are characterized by high power and low energy densities. A hybrid PEMFC/supercapacitor device (HPSD) with high energy and power densities was proposed and fabricated for the first time using a reduced graphene oxide/Nafion/Pt electrode in this study. The reduced graphene oxide (rGO) was a capacitive material, and Pt was used as the electrocatalyst. Nafion ionomers adsorbed onto the rGO sheets surface and connected the rGO sheets and the electrolyte (Nafion membrane), thus increasing the utilization rate and specific capacitance of rGO. During the half-cell tests, the rGO/Nafion/Pt electrode exhibited better pulse discharge and galvanostatic discharge performance than the conventional Nafion/Pt electrode. Due to the unique synergy of electrochemical reaction current and capacitance current during the discharge process, the HPSD exhibited a higher power density (26.2 kW kg⁻¹) than the PEMFC (23.9 kW kg⁻¹). The energy density (12.7 kWh kg⁻¹) exhibited by HPSD was close to that of the PEMFC (13.5 kWh kg⁻¹). Therefore, the concept of HPSD is to create a new method for developing next-generation electrochemical devices with high energy and power densities.     

Reduced graphene oxide supported nickel tungstate nano-composite electrocatalyst for anodic urea oxidation reaction in direct urea fuel cell

In recent time direct urea fuel cell (DUFC) emerges as a potential candidate for sustainable urea reach wastewater treatment and power generation. The efficiency of DUFC mainly governed by the anodic urea oxidation reaction (UOR) kinetics. The design and development of efficient electrocatlysts for UOR remains a key factor for practical utilization of DUFC. In current study, we present a single step hydrothermal synthesis of NiWO₄ NPs/rGO (h-NiWO₄ NPs/rGO) composite for UOR catalysis in alkaline medium. The synthesized NiWO₄ NPs/rGO composite offers a 218 mA/cm² UOR catalytic current density. Moreover, the h-NiWO₄ NPs/rGO composite retains its 94% UOR catalytic current after 1000 cyclic voltammetric cycles. Further, h-NiWO₄ NPs/rGO composite shows superior UOR catalytic performance than physical mixture of NiWO₄ NPs and rGO, NiWO₄ NPs, NiO/WO₃ physical mixture and only NiO with reference to catalytic current density, onset potential, and durability. The enhanced electrocatalytic activity of the h-NiWO₄ NPs/rGO composite attributed to the synergetic coupling of physiochemical properties of NiWO₄ NPs and rGO which improves the charge transfer generates larger electroactive surface and reduces catalyst poisoning. An air cathode DUFC with h-NiWO₄ NPs/rGO composite modified anode and Pt/C cathode produces a maximum power density of 5.1 mW/cm² and 927 mV open circuit potential.     

The electrochemical properties of reduced graphene oxide film with capsular pores prepared by using oxalic acid as template

By using oxalic acid (OA) as template and reducer, a novel approach is developed to prepare reduced graphene oxide films with capsular pores (C‐rGOFs) under a hydrothermal condition. The effect of preparation conditions including concentrations of OA and reaction temperatures on the films' structure and capacitive performances has been systematically investigated. The optimal C‐rGOF shows uniform capsule‐like morphology and exhibits a density of 1.18 g cm^?3. Tested by using a two‐electrode system, the optimal film shows gravimetric specific capacitance of about 234.9 F g^?1 and volumetric specific capacitance of 277.2 F cm^?3. Additionally, the optimal film which shows good rate capability can retain 63.9% of initial capacitance at high scan rate of 1.0 V s^?1, which is much higher than that of the controlling reduced graphene oxide film (rGOF, 180.5 F g^?1, 373.6 F cm^?3 and retain only 45.0% of its initial capacitance at 1.0 V s^?1). The cells assembled by the optimal C‐rGOF exhibit maximum energy density of 7.5 Wh kg^?1, power density of 16.9 kW kg^?1, and excellent cycling stability with 91.2% capacitance retention after 21 000 cycles. It is believed that this method can be developed as a useful strategy to prepare rGO‐based materials for energy storage applications.     

Heterostructural composite of few-layered MoS2/hexagonal MoO2 particles/graphene as anode material for highly reversible lithium/sodium storage

The heterostructural construction of metal disulfide/oxide is essential in the electrochemical performance as anode material for lithium- and sodium-ion batteries (LIBs and SIBs). In this work, an integrated composite of molybdenum disulfide (MoS₂) and hexagonal molybdenum dioxide (MoO₂) together enwrapped in reduced graphene oxide (rGO) is synthesized under hydrothermal condition. In the pelletizing MoS₂-MoO₂/rGO composite, rGO as substrate effectively prevents the restacking and pulverization of MoS₂-MoO₂ during a long cycling process. Meanwhile, the synergistic effect among the MoS₂, MoO₂, and rGO components are responsible for abundant active sites and shorten ionic transport channels. When evaluating as anode material for LIB, MoS₂-MoO₂/rGO sample presents excellent cyclic performance and still delivers a high capacity of 1062.3 mA h g⁻¹ after 120 cycles at 0.2 A g⁻¹; evaluating in a SIB at 0.04 A g⁻¹, it presents excellent cyclic performance and delivers 430 mA h g⁻¹ at the 80th cycle. The heterostructural composite MoS₂-MoO₂/rGO is one of the candidate anode materials for high-performance LIB and SIB.     

Nickel-cobalt layered double hydroxide ultrathin nanosheets coated on reduced graphene oxide nonosheets/nickel foam for high performance asymmetric supercapacitors

Here in, for the first time, we report a new and simple procedure for preparing reduced graphene oxide/nickel-cobalt double layered hydroxide composite on the nickel foam (Ni-Co LDH/rGO/NF) via a fast and simple two-step electrochemical method including potentiostatic routes in the presence of CTAB as a cationic surfactant. Graphene oxide coated nickel foam prepared by simple immersion method. After that, the prepared electrode reduced electrochemically to obtain rGO/NF electrode. Finally, the rGO/NF electrode was used as cathode for electrodeposition of Ni-Co LDH in the presence of CTAB as cationic surfactant. The prepared electrodes were characterized by field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), x-ray diffraction (XRD), fourier transform infrared spectroscopy (FTIR), Energy-dispersive X-ray spectroscopy (EDS), Brunauer, Emmett and Teller (BET) and electrochemical techniques such as voltammetry (CV), galvanostatic charge-discharge curves (GCD) and electrochemical impedance spectroscopy (EIS). The resulting electrode which prepared in the presence of CTAB afforded extremely high specific capacitance of 2133.3 F g^?1 at a current density of 4 A g^?1. FE-SEM, TEM and EDS mapping results showed that Ni-Co LDH nanosheets uniformly covered the surface of rGO/NF in the presence of CTAB, and is closely packed and thinner in thickness compared with the sample prepared in similar way without using surfactant. Such new thin and dense morphology facilitates electrolyte ions diffusion through the prepared electrode. A good cycling stability was obtained for the electrode in alkaline media. EIS measurements showed low values of internal resistance (R_s) and charge transfer resistance (R_ct), indicating that the prepared nanocomposite is a promising candidate for supercapacitor applications. The asymmetric supercapacitor (ASC) based on the Ni-Co LDH/CTAB/rGO/NF as a positive electrode and rGO/NF as a negative electrode was assembled and it exhibited a C_s of 71.4 F g^?1 at a current density of 2 A/g and correspondingly energy density of as high as 68 Wh kg^?1.     

Effect of rGO on Fe2O3–TiO2 composite incorporated NiP coating for boosting hydrogen evolution reaction in alkaline solution

Fe₂O₃–TiO₂ composite incorporated NiP coating is a known promising catalytic coating for electrocatalytic Hydrogen Evolution Reaction (HER). It is explored in the present study that the activity of the coating can be enhanced by incorporation of rGO. The Fe₂O₃–TiO₂/rGO, electrocatalyst is synthesized by a facile hydrothermal method. Various compositions of the Fe₂O₃–TiO₂/rGO incorporated NiP coatings on mild steel substrate are developed by a chemical reduction method. The developed Fe₂O₃–TiO₂/rGO composite coating exhibits effective hydrogen evolution reaction activity with a Tafel slope of 98 mV dec⁻¹ and a low overpotential of 96 mV at a current density of 10 mA cm⁻². The hydrogen evolution reaction mechanism comprises of Volmer (adsorption of Hydrogen atom) followed by Heyrovskii (reduction to H₂). The enhanced catalytic activity by the incorporation of rGO into the coating is due to three dimensional projections of nano Fe₂O₃–TiO₂ on the folded surface of rGO. It effectively enhances the electrochemically active surface area of the coated electrode. The electrode is highly stable during alkaline HER. These results reveal that Fe₂O₃–TiO₂/rGO can be treated as an effective electrocatalyst during HER from alkaline solutions. The conclusions pave the way for exploration of new similar catalysts for other applications.     

Enhanced electrochemical performance of nickel intercalated ZIF-67/rGO composite electrode for solid-state supercapacitors

Ni (Nickel) doped zeolitic-imidazolate framework (ZIF-67) has been prepared in presence of reduced graphene oxide (rGO) to realize a ZIF-67/rGO composite. The doping level of Ni and the ratio of rGO (wt%) in the composite have been optimized to attain desirable redox activity and electrical conductivity. A partial incorporation of redox active Ni ions to substitute Co (cobalt) ions in ZIF-67 has resulted in better electrochemical characteristics by inducing additional pseudocapacitance. A finalized composite with 33% Ni and 20% of rGO (i.e, Ni₃₃/ZIF-67/rGO₂₀) has been used as a supercapacitor electrode material to achieve a high specific capacitance of 304 F/g at a current density of 1 A/g in the presence of 1 M H₂SO₄ as an aqueous electrolyte. The above electrode has also been tested for an all-solid-state symmetric supercapacitor in the presence of a polymer gel electrolyte (PVA/1 M H₂SO₄). This device delivered high values of power and energy densities, i.e., 1 kW/kg and 21.5 Wh/kg, respectively. The device also exhibited an excellent cyclic stability. About 87% of capacitance could be retained even after 4500 charge-discharge cycles. The device has shown superior results for a working potential window of 0–2 V. The practical usefulness of the device has been demonstrated by preparing a symmetrical supercapacitor, which could energize a white LED for 8 min upon a charging of only 40 s.     

Synthesis of nickel hydroxide/reduced graphene oxide composite thin films for water splitting application

Facile synthesis of highly efficient and low-cost electrocatalyst for oxygen evolution reaction (OER) is important for large-scale hydrogen production. Herein, nickel hydroxide/reduced graphene oxide (Ni(OH)₂/rGO) composite thin film was fabricated using dip-coating followed by electrodeposition method on Ni foam substrate at room temperature. The deposited composite film shows amorphous nature with ultra-thin Ni(OH)₂ nanosheets vertically coated on rGO surface, which provides large electrochemical surface area and abundant catalytically active sites. It exhibits a low overpotential of 260 mV @10 mA cm⁻² as compared to the pristine electrodes and excellent long-term stability up to 20 hours in 1 M KOH solution. The electrochemical active surface area and Tafel slope of the composite electrode are 20.2 mF cm⁻² and 35 mV dec⁻¹, respectively. The superior water oxidation performance is a result of high catalytically active sites and improved conductivity of the composite electrode.     

Enhanced photoelectrochemical water splitting in hierarchical porous ZnO/Reduced graphene oxide nanocomposite synthesized by sol-gel method

Today the utilization of solar energy to split water and its conversion to hydrogen and oxygen has been considered as a powerful way to solve the environmental crisis. Hierarchical porous nanostructured ZnO and ZnO/reduced graphene oxide (rGO) composite photoanodes are synthesized by innovated sol-gel method using triethylenetetramine (TETA) as a stabilizer. The hierarchical porous ZnO structure containing large agglomerates each consisting of tiny nanoparticles are formed. The X-ray diffraction analysis and Raman spectroscopy confirm the in-situ reduction of graphene oxide sheets during synthesis and formation of ZnO/rGO nanocomposite. Although the band gap and transmittance of the porous nanocomposites do not dramatically change by rGO addition, the main photoluminescence peak quenches entirely showing prolonging exciton lifetime. The ZnO/rGO porous structure achieved remarkably improved current density (1.02 mA cm^?2 at 1.5 V vs. Ag/AgCl) in 1 wt% rGO, up to 12 times higher compared to the bare ZnO (0.09 mA cm^?2 at 1.5 V vs. Ag/AgCl), which attributes to positive role of ZnO hierarchical porous structure and rGO electron separation/transportation. These findings provide new insights into the broad applicability of this methodology for promising future semiconductor/graphene composite in the field of photoelectrochemical water splitting.     

Co2FeO4@rGO composite: Towards trifunctional water splitting in alkaline media

Development of efficient, low cost and multifunctional electrocatalysts for water splitting to harvest hydrogen fuels is a challenging task, but the combination of carbon materials with transition metal-based compounds is providing a unique and attractive strategy. Herein, composite systems based on cobalt ferrite oxide-reduced graphene oxide (Co₂FeO₄) @(rGO) using simultaneous hydrothermal and chemical reduction methods have been prepared. The proposed study eliminates one step associated with the conversion of GO into rGO as it uses direct GO during the synthesis of cobalt ferrite oxide, consequently rGO based hybrid system is achieved in-situ significantly, the optimized Co₂FeO₄@rGO composite has revealed an outstanding multifunctional applications related to both oxygen evolution reaction (OER) and hydrogen counterpart (HER). Various metal oxidation states and oxygen vacancies at the surface of Co₂FeO₄@rGO composites guided the multifunctional surface properties. The optimized Co₂FeO₄@rGO composite presents excellent multifunctional properties with onset potential of 0.60 V for ORR, an overpotential of 240 mV at a 20 mAcm^?2 for OER and 320 mV at a 10 mAcm^?2 for HER respectively. Results revealed that these multifunctional properties of the optimized Co₂FeO₄@ rGO composite are associated with high electrical conductivity, high density of active sites, crystal defects, oxygen vacancies, and favorable electronic structure arisinng from the substitution of Fe for Co atoms in binary spinel oxide phase. These surface features synergistically uplifted the electrocatalytic properties of Co₂FeO₄@rGO composites. The multifunctional properties of the Co₂FeO₄@ rGO composite could be of high interest for its use in a wide range of applications in sustainable and renewable energy fields.     

Synthesis of ultrafine low loading Pd–Cu alloy catalysts supported on graphene with excellent electrocatalytic performance for formic acid oxidation

Here, surfactant free composite catalysts (Pd–Cu/rGO) with Pd–Cu alloy nanoparticles uniformly distributed on graphene sheets are successfully prepared via a facile hydrothermal approach. Compared with pure Pd/rGO catalyst, the introduction of copper could dramatically enhance the performance of the catalyst in the electrocatalytic formic acid oxidation (FAO) due to the strain effect and the ligand effect. With the optimized atomic ratio of 3:1 between palladium and copper, the alloy nanoparticle shows the smallest size of 2.12 nm, thus endowing the composite catalyst with highest catalytic efficiency. With Pd load as low as 14.5%, a maximum mass current density of 1580 mA mg_Pd⁻¹, and residual current of 69.93 mA mg_Pd⁻¹ at 3000 s was achieved with our Pd₃Cu₁/rGO catalyst in the electrocatalytic FAO process.     

A high-performance three-dimensional micro supercapacitor based on self-supporting composite materials

This paper introduces a silicon three-dimensional (3D) micro supercapacitor, featured by using self-supporting nano porous composite materials and interdigital electrodes with high-aspect-ratio. A way to prepare self-supporting materials has been developed, and composites that contain an activated carbon as the active component have been studied and designed to meet the requirements for adequate specific capacitance, good conductivity and strong structure. By combining the designed composite with microfabrication techniques, a micro supercapacitor with high-aspect-ratio interdigital electrodes has been achieved. Electrochemical characterization results of the prototype with NaNO₃ electrolyte demonstrate that the 3D supercapacitor exhibits an outstanding overall performance. A large capacitance of 90.7 mF cm⁻² and a fast power of 51.5 mW cm⁻² are calculated. Robust stability and high charge/discharge efficiency are also observed. Moreover, this study provides a scalable device built by compatible fabrication method, which is applicable to the integration of high-performance supercapacitors on chip.     

Hierarchical design of Ni(OH)2/MnMoO4 composite on reduced graphene oxide/Ni foam for high-performances battery-supercapacitors hybrid device

Design and synthesis advanced battery-type electrode materials with outstanding electrical conductivity and remarkable theoretical specific capacity are crucial to enhance the comprehensive performances for battery-supercapacitors (SCs). Herein, Ni(OH)₂/MnMoO₄ composite on reduced graphene oxide/Ni foam (rGO/NF) was successfully fabricated through the hydrothermal method and potentiostatic electrodeposition (Ni(OH)₂/MnMoO₄/rGO/NF). The unique honeycomb structure and the efficient synergistic effects among MnMoO₄ and Ni(OH)₂ of the as-prepared battery type electrode, as well as outstanding electronic conductivity of the reduced graphene oxide, were beneficial to the enhanced electrochemically active sites and increased specific capacity. Ni(OH)₂/MnMoO₄/rGO/NF composite employed for SCs yielded the maximum specific capacity of 1329.1 C g⁻¹ and a superb cycle property of 86.8% during 5000 cycles. Furthermore, the battery-supercapacitor hybrid (BSH) device with the Ni(OH)₂/MnMoO₄/rGO/NF and active carbon (AC) as-prepared samples showed the energy density of 61.4 W h kg⁻¹ at the power density of 428.4 W kg⁻¹. The capacity retention of the as-fabricated hybrid device reached 96.4% over 7000 cycles. Those consequences tested that the Ni(OH)₂/MnMoO₄/rGO/NF composite should be the promising category of battery-type electrodes materials of the next generation energy storage devices for the high-performances SCs.     

Activated charcoal and reduced graphene sheets composite structure for highly electro-catalytically active counter electrode material and water treatment

In quest of finding a sustainable solution for metal-free counter electrode materials, reduced graphene oxide (rGO) is emerged as the best alternative due to its intrinsic high electrocatalytic activity. However, owing to its two-dimensional sheets like structure, there is re-stacking of rGO sheets, which reduces exposed surface area and hinders in electrolyte diffusion. To avoid these issues, activated charcoal (AC) is explored as an active spacer material between rGO sheets, for the first time. By loading an optimum concentration of AC in rGO, a high porosity, high conductivity, and high concentration of active sites were gathered in the single composite structure. Such synchronized features of the proposed composite were utilized for Pt-free counter electrode application in dye-sensitized solar cell (DSSc). The composite structure showed high electrocatalytic activity, with a low charge transfer resistance of 0.7 Ω, which is far lower than Pt and rGO (8.5 Ω and 7.5 Ω). The DSSc fabricated with optimized composite showed power conversion efficiency of 8.6%, compared to Pt-based DSSc with 7.9% efficiency. Additionally, the potential of the electrode was also tested for the electro-photocatalytic (99%) degradation of methylene blue dye from water, in 60 min. The proposed highly efficient nanocomposite structure possesses the highest efficiency as compared to other previously studied rGO based counter-electrodes.     

Reduced graphene oxide as an efficient support for CdS-MoS2 heterostructures for enhanced photocatalytic H2 evolution

Cadmium sulphide nanorods-reduced graphene oxide-molybdenum sulphide(CdS-rGO-MoS₂) composites were successfully synthesized using hydrothermal process for enhancing the interfacial contact between CdS nanorods and MoS₂ layer. The good contact between CdS and MoS₂ is important for improving the photocatalytic hydrogen (H₂) evolution. The morphological and structural studies showed the production of highly pure CdS phase with nanorod-like structure dispersed on rGO-MoS₂ layer. X-ray photoelectron spectroscopy (XPS) and Raman results confirmed the reduction of graphene oxide (GO) into reduced graphene oxide (rGO). The higher photocurrent density of CdS-rGO-MoS₂ composites compared to CdS/MoS₂ and the fluorescence quenching observed for this composite provided some evidence for an inhibition of electron-hole recombination, which leads to a longer life time of the photogenerated carriers. Fast electron transfer can occur from CdS nanorods by the bidimensionnel rGO area to MoS₂ layer due to the intimate interfacial contact. Composite CdS-rGO-MoS₂ with 20 wt% rGO was found to be the most effective photocatalyst for H₂ evolution (7.1 mmol h^?1g^?1). The good photocatalytic performance arose from the positive synergistic effect between CdS, rGO and MoS₂ elements.     

Enhanced capacitance and rate capability of graphene/polypyrrole composite as electrode material for supercapacitors

Graphene and polypyrrole composite (PPy/GNS) is synthesized via in situ polymerization of pyrrole monomer in the presence of graphene under acid conditions. The structure and morphology of the composite are characterized by X-ray diffraction (XRD), Raman spectroscopy, Fourier transform infrared spectrometer (FTIR), X-rays photoelectron spectroscopy (XPS) and transmission electron microscope (TEM). It is found that a uniform composite is formed with polypyrrole being homogeneously surrounded by graphene nanosheets (GNS). The composite is a promising candidate for supercapacitors to have higher specific capacitance, better rate capability and cycling stability than those of pure polypyrrole. The specific capacitance of PPy/GNS composite based on the three-electrode cell configuration is as high as 482 F g⁻¹ at a current density of 0.5 A g⁻¹. After 1000 cycles, the attenuation of the specific capacitance is less than 5%, indicating that composite has excellent cycling performance.     

Polymer-graphene hybride decorated Pt nanoparticles as highly efficient and reusable catalyst for the dehydrogenation of dimethylamine–borane at room temperature

Addressed herein, we report a reduced graphene oxide (rGO) nanosheet coupled with polyaniline (PANI) for platinum (Pt) nanoparticles as supporting materials. The PANI-coupled rGO (PANI@rGO) nanosheet is prepared by a simple one-step chemical assembly strategy, and Pt nanoparticles are anchored on the support of PANI@rGO through the reaction of PANI with a platinum salt. The designed PANI efficiently exposes the surface of rGO sheets and stabilizes metal nanoparticles. Consequently, the Pt@PANI-rGO catalyst exhibits good reusability, durability and high catalytic performance for dimethylamine–borane dehydrogenation reaction. The structure morphology and properties of Pt@PANI-rGO NPs were characterized by using several different techniques such as UV–Vis, XPS, TEM, XRD and HR-TEM-EDX analyses. This newly prepared catalyst can be reused again at low concentrations and temperature. They showed a high turnover frequency (42.94 h^?1) and low E_a value of 15.1 ± 2 kJ/mol for DMAB dehydrocoupling in the ambient conditions. The proposed nano architecture offers a new pathway to promote the performances of rGO in various applications; moreover, this work provides a powerful and universal synthetic strategy for such an architecture.