The development of transition metal compounds (TMCs) and conductive polymers composite catalysts substitute for the traditional scarce Pt-based catalysts of counter electrodes (CEs) has been recognized as one of the distinguishing paths to enhance power conversion efficiency (PCE) and decrease manufacturing costs of dye-sensitized solar cells (DSSCs). At present, various thin film preparations have been developed and applied to prepare assortment CEs. Herein, both polyaniline (PANI) and CuWO 4 film were prepared, and further to fabricate layer-by-layer composite CEs of CuWO 4 /PANI, PANI/CuWO 4 , CuWO 4 /PANI/CuWO 4 , PANI/CuWO 4 /PANI, aiming to promote the charge transfer capability and thus improve catalytic activity. And then, PANI, CuWO 4 and four composite layered CEs obtained PCE values of 5.14, 5.64, 5.96, 6.21, 4.96 and 4.24% toward the regeneration of I 3 − /I − redox couples in the assembled DSSCs, respectively. Particularly, the fascinating performance of the bilayer PANI/CuWO 4 CEs inherits the excellent electrical conductivity and the abundant porous structure of PANI skeletons for effective electrolyte diffusion. Meanwhile, the CuWO 4 layer was coupled to the layers of PANI by thermal activation annealing treatment to furnish rich inner active sites for the regeneration of I 3 − /I − couples. Benefit from the synergistic effects of PANI and CuWO 4 , the as-prepared PANI/CuWO 4 CEs manifests the highest PCE of 6.21%, indicating an inspiring strategy by the layered assembly Pt-free CEs with the cost effective and high-performance as an alternative Pt-based catalyst for DSSC.
By increasing the activity and specific properties of the catalyst during oxygen reduction reactions (ORR), we hope to improve fuel cell performance and energy conversion efficiency. Using a single microwave step, the graphene oxide-decorated iron phthalate catalyst (FePcNs@GO) nanocomposites were synthesised. Some analytical techniques were used to validate the morphology and composition of Fe catalyst/graphene (FePcGO) and FePcNs@GO. In an oxygen-saturated environment, we conducted the ORR electrocatalytic studies on the prepared materials. The results demonstrate that when FePcNs@GO is combined with graphene oxide, it exhibits excellent electrochemical properties. In comparison to commercial FePc and 20% Pt/C, the overpotential is significantly lower. Under nitrogen-saturated conditions, the Fe 2+/3+ redox form potential in FePcNs@GO exhibits a more positive behaviour, which favours strong interactions between Fe 2+ and O 2 . In this work, we demonstrate that platinum-free catalysts have potential applications in ORR.
Vanadium-based carbides have been applied as Pt-free counter electrodes (CEs) electro-catalysts for dye-sensitized solar cells (DSSCs) due to the advantages of earth-abundant reserves, diverse composition , ease modification, and low cost. Herein, the polyoxovanadate (NH 4 ) 2 V 6 O 16 as V source assisted by dicyandiamide (C 2 H 4 N 4 ) as C source via simply physical mixing by ball-milling to assemble VC@C precursors. And then, five different VC@C composites derived from precursors with mass ratios of dicyandiamide to polyoxovanadate of 5:1, 10:1, 15:1, 20:1 and 25:1 at 900 °C, and further achieved power conversion efficiencies (PCEs) of 5.4%, 5.6%, 6.6%, 6.2% and 5.1% as CEs for regenerate traditional I 3 − /I − couple in the encapsulated DSSCs, respectively. The effects of different mass ratio of dicyandiamide on the catalytic performances of VC@C composite CEs were also assessed using cyclic voltammetry , electrochemical impedance spectroscopy and Tafel polarization experiments. The photocurrent-photovoltage ( J - V ) results indicated that VC@C composites CEs had high conductivity and rich number of active sites, which indicated that VC@C composites could be a cost-effective and high-performance alternative Pt-based CEs catalyst for DSSCs.
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