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Copper(II)phthalocyanine-incorporated metal organic framework (CuPc/MOF) composite material was synthesized for application as an electrocatalyst for hydrogen evolution reaction (HER). The composite exhibited excellent electroactivity compared to the unmodified MOF, as confirmed by the diffusion coefficients (D) values of 3.89 × 10−7 and 1.57 × 10−6 cm2 s−1 for MOF and CuPc/MOF, respectively. The D values were determined from cyclic voltammetry (CV) experiments performed in 0.1 mol L−1 tetrabutylammonium perchlorate/dimethyl sulfoxide (TBAP/DMSO) electrolyte. The Tafel slope determined from the CV data of CuPc/MOF-catalysed HER for 0.450 mol L−1 H2SO4, was 176.2 mV dec−1, which was higher than that of the unmodified MOF (158.3 mV dec−1). The charge transfer coefficients of MOF and CuPc/MOF were close to 0.5, signifying the occurrence of a Volmer reaction involving either the Heyrovsky or the Tafel mechanism for hydrogen generation. For both MOF and CuPc/MOF, the exchange current density (i0) improved with increase in the concentration of the hydrogen source (i.e. 0.033–0.45 mol L−1 H2SO4) Nonetheless, the CuPc/MOF composite had a higher i0 value compared with the unmodified MOF. Thus CuPc/MOF has promise as an efficient electrocatalyst for HER.

Herein, we report on the in-situ chemical polymerization of polyaniline (PANI) doped with zinc-based zeolitic benzimidazolate framework (ZnZIF) to fabricate the PANI-ZnZIF composite for electrochemical hydrogen gas sensing. Fourier-transform infrared and Raman studies of PANI-ZnZIF composite revealed the presence of functional groups corresponding to both ZnZIF and PANI. Both X-ray diffraction and simultaneous thermal analyses showed the co-existence of both PANI and ZnZIF in the composite supported by the decrease in crystallite size and the improvement in the thermal stability, respectively. The scanning electron microscopy, transmission electron microscopy, energy dispersive X-ray spectroscopy, and selected area electron diffraction revealed that PANI nanofibers wrapped the cube nanofiber-like structures of ZnZIF. The square wave voltammetry, cyclic voltammetry (CV) and chronoamperometry presented good electrochemical performance indicated by an increase in current response with 3 wt% loading of ZnZIF. The high electrochemical current response is due to extraordinary specific surface area, more accessible active sites available for the electrolyte provided by ZnZIF and high conductivity supplied by PANI. Moreover, Tafel parameters and Turnover frequency values derived from CV showed an improvement in the catalytic hydrogen evolution of PANI-ZnZIF composite. The resulting PANI-ZnZIF composite was found to be highly responsive to hydrogen gas as indicated by higher current response and sensitivity (10.8 μA mM H2), faster steady state response time of 4 s accompanied by lower detection limit of 5.27 μM as compared to pure PANI.

With growth in civilisation and industrialisation, there is an increase in the release of toxic heavy metal ions and dyes into water system, which is of public concern. As a result, appropriate treatment methods have to be implemented in order to mitigate and prevent water pollution. The discovery of nanotechnology has led to the development and utilisation of various nanoadsorbent for the removal of pollutants from water. PANI nanostructures and nanocomposites are noble adsorbents that have gained popularity in addressing water pollution issues and have been reported in literature. In this chapter, the main focus is on the synthesis of PANI nanocomposites and nanostructures and their application as efficient adsorbents for water treatment. Detailed discussions on different synthetic routes and characterisation have been dedicated to applications of these materials and are compared for the adsorptive removal of heavy metal ions and dyes from water.

Pd-supported copper phthalocyanine/metal organic frameworks (Pd@CuPc/MOF) composite was synthesized by the reaction between CuPc and MOF followed by electroless Pd plating. The structural properties of MOF, Pd@MOF and Pd@CuPc/MOF composite were characterized using X-ray diffraction (XRD), Fourier transform infrared (FTIR), simultaneous thermal analysis (STA), ultraviolet–visible spectroscopy (UV–vis), scanning electron microscopy (SEM/EDS) and Brunauer-Emmett-Teller (BET). The XRD, UV–vis and FTIR analyses showed that Pd was coated on CuPc/MOF composite. SEM and EDS results revealed that Pd nanoparticles were well-dispersed and anchored tightly on the composite. The thermal stability of MOF increased upon addition of Pd and CuPc. The electrochemical hydrogen evolution reaction (HER) performance of the synthesized materials was studied by cyclic voltammetry (CV) and Tafel analysis. The Tafel slope of the composite was 176.9 mV/dec and the transfer coefficient of 0.67 which is close to 0.5. The HER results revealed that the Pd@CuPc/MOF composite has better catalytic characteristic such as high catalytic activity and lowest onset potential compared to MOF. More importantly, the significant enhancement of HER performance at ambient temperature for the composite with Pd content can be ascribed to the hydrogen spillover mechanism in such system.

Advanced materials for hydrogen evolution reaction are central to the area of renewable energy. Here, we developed a solvothermal synthesis of metal organic framework (MOF) nanoparticles decorated with poly (3-aminobenzoic acid) (PABA) referred as MOF-3.6 wt.%-PABA and MOF–5 wt.%-PABA composites. The parent material (MOF) and composites were characterized by ultraviolet visible (UV-vis) and Fourier transform infrared (FTIR) spectroscopy, powder X-ray diffraction (XRD), thermogravimetric analysis (TGA), scanning electron microscope (SEM), transmission electron microscope (TEM), energy dispersive X-ray spectroscopy (EDS, EDX), selected area electron diffraction (SAED) and cyclic voltammetry (CV). Detailed structural and morphological characterizations established that PABA interacts with MOF on the external surface as observed by appearance of rough surface of the composites. The XRD and SAED showed that MOF and composites are crystalline and the presence of PABA did not alter the crystallinity of the material. Experiments probing the thermal, electrochemical and photophysical properties revealed that the composites were very stable and robust and had exceptionally properties. Significant hydrogen evolution reaction (HER) using CV and Tafel plots, was generated by MOF and composites in dimethyl sulfoxide/tetrabutylammonium perchlorate (DMSO/TBAP) supporting electrolyte in the presence of hydrogen source by applying a negative potential to the electrode.

A novel hybrid-hybrid nanocomposite based on 4-tetranitro copper(II)phthalocyanine (TNCuPc) grown on metal organic frameworks (MOF) as a noble metal-free catalyst for hydrogen evolution reaction (HER) was developed by a simple impregnation method. The structure, surface area and the morphology of the bare MOF, TNCuPc and the TNCuPc/MOF composite were characterized by X-ray diffraction, Fourier transform infrared spectroscopy, ultraviolet-visible spectroscopy, Brunauer-Emmet-Teller, scanning electron microscopy, transmission electron microscopy and simultaneous thermal analysis. The electrocatalytic activity of the samples towards the HER was evaluated using electrochemical impedance spectroscopy (EIS) and cyclic voltammetry, exchange current density, i0, Tafel slope value, b, as well as charge transfer coefficient, α. The spectroscopic analyses indicated a successful synthesis of TNCuPc and its composite. The morphological results showed the development of rod-like structures of TNCuPc on the surface of the MOF. The composite exhibited an onset potential of about −0.713 V vs. Ag/AgCl in 0.1 M TBAP/DMSO and 0.3 M H2SO4 solutions, which is 44 mV and 9 mV more positive than that of MOF and TNCuPc respectively. The composite showed the rate determining step (RDS) to be the Volmer reaction in conjunction with either Heyrovsky or Tafel reaction as the RDS due to the Tafel slope value of 147 mV/dec and an α of 0.4. The i0 value of the TNCuPc/MOF composite was about 1.6 times that of the bare MOF. The EIS results showed the charge transfer resistance (Rct) of 12.6 kΩ for the TNCuPc/MOF composite as compared to MOF and TNCuPc values of 41 and 18.6 kΩ, respectively, demonstrating an excellent conductivity of the composite. In addition, Rct values of materials follow the sequence, blank

Polyaniline-based metal-organic framework (PANI/MOF) composite was synthesized by chemical oxidation of aniline monomer in the presence of MOF content for practical usages as effective hydrogen production. PANI and composite were characterized by ultraviolet visible (UV-vis) and Fourier transform infrared (FTIR) spectroscopy, atomic absorption spectroscopy (AAS), powder X-ray diffraction (XRD), thermogravimetric analysis (TGA), scanning electron microscope (SEM), transmission electron microscope (TEM), energy-dispersive X-ray spectroscopy (EDS, EDX), selected area electron diffraction (SAED) and cyclic voltammetry (CV). Detailed structural and morphological characterizations established that PANI is wrapping MOF. The XRD, Raman and FTIR analyses showed that MOF was incorporated on the backbone of PANI through electrostatic interactions. This was supported by AAS analysis, revealing the amount of copper metal present in the composite. The determined energy band gap of the composite was in good agreement with previously reported catalysts for hydrogen evolution reaction (HER). Experiments probing the thermal, electrochemical, HER and photophysical properties revealed that the composite was very stable and robust and had exceptionally properties. Significant HER was generated by the composite in dimethyl sulphoxide/tetrabutylammonium perchlorate (DMSO/TBAP) supporting electrolyte in the presence of hydrogen source by applying a negative potential to the electrode. PANI and MOF also generated a weak HER as compared to composite.