Reduced graphene oxide-multiwalled carbon nanotubes hybrid film with low Pt loading as counter electrode for improved photovoltaic performance of dye-sensitised solar cells

In this work, the role of reduced graphene oxide (rGO) with hyperbranched surfactant and its hybridisation with multiwalled carbon nanotubes (MWCNTs) and platinum (Pt) nanoparticles (NPs) as counter electrode (CE) were investigated to determine the photovoltaic performance of dye-sensitised solar cells (DSSCs). Sodium 1,4-is(neopentyloxy)-3-(neopentyloxycarbonyl)- 1,4-dioxobutane-2-sulphonate (TC14) surfactant was utilised as dispersing and stabilising agent in electrochemical exfoliation to synthesise graphene oxide (GO) as initial solution for rGO production prior to its further hybridisation and fabrication as thin film. A chemical reduction process utilising hydrazine hydrate was conducted to produce rGO due to the low temperature process and water-based GO solution. Subsequently, hybrid solution was prepared by mixing 1 wt% MWCNTs into the produced rGO solution. TC14-rGO and TC14-rGO_MWCNTs hybrid solution were transferred into fluorine-doped tin oxide substrate to fabricate thin film by spraying deposition method. Finally, the CE films were prepared by coating with thin Pt NPs. Photoanode film was prepared by a two-step process: hydrothermal growth method to synthesise titanium dioxide nanowires (TiO2 NWs) and subsequent squeegee method to apply TiO2 NPs. According to solar simulator measurement, the highest energy conversion efficiency (η) was achieved by using CE-based TC14-rGO_MWCNTs/Pt (1.553%), with the highest short current density of 4.424 mA/cm2. The highest η was due to the high conductivity of CE hybrid film and the morphology of fabricated TiO2 NWs/TiO2 NPs. Consequently, the dye adsorption was high, and the photovoltaic performance of DSSCs was increased. This result also showed that rGO and rGO_MWCNTs hybrid can be used as considerable potential candidate materials to replace Pt gradually

Reduced graphene oxide-multiwalled carbon nanotubes hybrid film with low Pt loading as counter electrode for improved photovoltaic performance of dye-sensitised solar cells

In this work, the role of reduced graphene oxide (rGO) with hyperbranched surfactant and its hybridisation with multiwalled carbon nanotubes (MWCNTs) and platinum (Pt) nanoparticles (NPs) as counter electrode (CE) were investigated to determine the photovoltaic performance of dye-sensitised solar cells (DSSCs). Sodium 1,4-bis(neopentyloxy)-3-(neopentyloxycarbonyl)- 1,4-dioxobutane-2-sulphonate (TC14) surfactant was utilised as dispersing and stabilising agent in electrochemical exfoliation to synthesise graphene oxide (GO) as initial solution for rGO production prior to its further hybridisation and fabrication as thin film. A chemical reduction process utilising hydrazine hydrate was conducted to produce rGO due to the low temperature process and water-based GO solution. Subsequently, hybrid solution was prepared by mixing 1 wt% MWCNTs into the produced rGO solution. TC14-rGO and TC14-rGO_MWCNTs hybrid solution were transferred into fluorine-doped tin oxide substrate to fabricate thin film by spraying deposition method. Finally, the CE films were prepared by coating with thin Pt NPs. Photoanode film was prepared by a two-step process: hydrothermal growth method to synthesise titanium dioxide nanowires (TiO2 NWs) and subsequent squeegee method to apply TiO2 NPs. According to solar simulator measurement, the highest energy conversion efficiency (η) was achieved by using CE-based TC14-rGO_MWCNTs/Pt (1.553%), with the highest short current density of 4.424 mA/cm2 . The highest η was due to the high conductivity of CE hybrid film and the morphology of fabricated TiO2 NWs/TiO2 NPs. Consequently, the dye adsorption was high, and the photovoltaic performance of DSSCs was increased. This result also showed that rGO and rGO_MWCNTs hybrid can be used as considerable potential candidate materials to replace Pt gradually

Effect of surfactants’ tail number on the PVDF/GO/TiO2-based nanofiltration membrane for dye rejection and antifouling performance improvement

In this work, the novel utilisation of customised double- and triple-tail sodium bis(3,5,5-trimethyl-1-hexyl) sulphosuccinate (AOT4) and sodium 1,4-bis(neopentyloxy)-3-(neopentyloxycarbonyl)-1,4-dioxobutane-2-silphonate (TC14) surfactants to assist the direct graphene oxide (GO) synthesis via electrochemical exfoliation utilising dimethylacetamide (DMAc) as a solvent were investigated. The synthesised DMAc-based GO and titanium dioxide (TiO2) nanoparticles were then used to fabricate polyvinylidene fluoride (PVDF)-based nanofiltration (NF) membranes by the non-solvent-induced phase separation method. The incorporation of GO and TiO2 as hydrophilic nanoparticles were to enhance membrane hydrophilicity. The utilisation of higher surfactants’ tail number obviously alters the fabricated membrane’s morphology which further affects its performance for dye rejection and antifouling ability. Higher surfactants’ tail number resulted in higher oxidation process which then provided more interaction between the GO and PVDF. Based on the dead-end cell measurement, PVDF/TC14-GO/TiO2 presented a slightly higher dye rejection efficiency of 92.61% as compared to PVDF/AOT4-GO/TiO2 membrane (92.39%). However, PVDF/TC14-GO/TiO2 possessed three times higher water permeability (48.968 L/m2 h MPa) than PVDF/AOT4-GO/TiO2 (16.533 L/m2 h MPa) and also higher hydrophilicity as presented by lower contact angle (65.4 ± 0.17°). This confirmed that higher surfactants’ tail number improved the fabricated membrane’s performance. Both fabricated membranes also exhibited high flux recovery ratio (FRR) (> 100%) which indicated better antifouling properties

Titanium dioxide/agglomerated-free reduced graphene oxide hybrid photoanode film for dye-sensitized solar cells photovoltaic performance improvement

In this work, the role of agglomerated-free reduced graphene oxide (rGO) in the modification of titanium dioxide (TiO 2 ) photoanode film was investigated for the enhancement of photovoltaic performance in dye-sensitized solar cells (DSSCs). The rutile TiO 2 nanorods–nanoflowers (NRs–NFs) and the photoanode layer consisting of anatase TiO 2 nanoparticles (NPs) were synthesized by the simple hydrothermal growth and squeegee method, respectively. Post-annealing treatment of TiO 2 NRs–NFs was also done in order to investigate its effect on the DSSCs performance. Meanwhile, the rGO solution was produced by reducing a graphene oxide (GO) solution utilizing hydrazine hydrate via a chemical reduction process. The initial GO solution was synthesized by electrochemical exfoliation assisted by a hyper-branched sodium 1,4-bis (neopentyloxy)-3-(neopentyloxycarbonyl)-1,4-dioxobutane-2-sulphonate (TC14) surfactant. The produced TC14-rGO was also hybridized with multi-walled carbon nanotubes (MWCNTs), which then coated by thin platinum (Pt) NPs (TC14-rGO_MWCNTs/Pt) and used as counter electrode (CE) thin film. Based on solar simulator measurements, the highest energy conversion efficiency (η) (1.559%) was achieved by TiO 2 NRs–NFs/TC14-rGO/TiO 2 NPs hybrid photoanode film with the short current density (J sc ), open circuit voltage (V oc ), and fill factor (FF) of 3.275 mA/cm 2 , 0.747 V, and 53.5, respectively as compared to others fabricated photoanode films; non-ann TiO 2 NRs–NFs/TiO 2 NPs (1.215%), ann TiO 2 NRs–NFs/TiO 2 NPs (1.462%), and TiO 2 NRs–NFs/TiO 2 NPs/TC14-rGO (0.525%). This result shows that the utilization of TC14-rGO for both photoanode and CE film increases the conductivity of the film. High η was also supported by high dye adsorption promoted by TiO 2 NPs as the top photoanode layer

Effects of TiO2 phase and nanostructures as photoanode on the performance of dye-sensitized solar cells

In this study, different titanium dioxide (TiO2) nanostructures and phase were investigated as photoanode film for application in dye-sensitized solar cells. Rutile TiO2 nanorods (NRs)-nanotrees (NTs) and TiO2 NRs-microcauliflowers (MCFs) were synthesized via hydrothermal method for different time. The mixed phase of rutile-anatase film was fabricated by applying TiO2 nanoparticles paste on the synthesized TiO2 NRs-NTs via squeegee method. The counter electrode film was fabricated by spraying deposition and sputtering methods of reduced graphene oxide–multi-walled carbon nanotubes and platinum, respectively. Solar simulator measurement revealed that higher energy conversion efficiency (1.420%) and short-circuit current density (3.584 mA cm-2) were achieved by using rutile TiO2 NRs-MCFs film. The utilization of a thick rutile film with microparticle structures increases dye adsorption, and thus enhances the electron excitation. Graphic abstract: [Figure not available: see fulltext.]

Incorporation of electrochemically exfoliated graphene oxide and TiO2 into polyvinylidene fluoride-based nanofiltration membrane for dye rejection

In this work, the novel direct synthesis method of dimethylacetamide-based graphene oxide (GO) was performed through electrochemical exfoliation assisted by commercially available single-tail sodium dodecyl sulphate (SDS) surfactant. Then, the synthesised GO (SDS–GO) was incorporated into polyvinylidene fluoride (PVDF) solution to produce a nanofiltration (NF) membrane through the phase immersion method. The addition of GO into the preparation of membrane solution alters the membrane morphology and improves the hydrophilicity. TiO2 was also used as an additive for the NF membrane fabrication to further increase the membrane hydrophilicity. The fabricated PVDF/SDS–GO/TiO2 and PVDF/SDS–GO NF membranes were compared with pure PVDF membrane. Then, the fabricated NF membranes were tested for methylene blue (MB) rejection with 10 ppm MB concentration. On the basis of the dead-end cell measurement operated at the pressure of 2 bar, the PVDF/SDS–GO/TiO2 presents high MB rejection (92.76%) and the highest dye flux (7.770 L/m2 h). This dye flux value was sevenfold higher than that of pure PVDF membrane (1.146 L/m2 h) which was due to the utilisation of both GO and TiO2 that improved the membrane hydrophilicity as indicated by the lowest contact angle (64.0 ± 0.11°). High porosity (57.46%) also resulted in the highest water permeability (4.187 L/m2 h bar) of the PVDF/SDS–GO/TiO2 NF membrane