Electrospun Cu-Deposited Flexible Fibers as an Efficient Oxygen Evolution Reaction Electrocatalyst

Developing oxygen evolution reaction (OER) catalysts with high activity, long-term durability, and at low cost remains a great challenge. Herein, we report the high activity of fibrous Cu-based catalysts. The synthesis process is simple and scalable. Electrospinning method was selected to synthesize fibrous polymer substrates (Poly(vinylidene fluoride-co-hexafluoropropylene, PVdF-HFP), which are then covered by Cu via electroless deposition. Cu-deposited PVdF-HFP with different microstructures having smooth and roughened surfaces were also synthesized by drop-casting and impregnation method, respectively, to emphasize the importance of the microstructures on OER activity. The OER activity and durability were studied by linear sweep voltammetry, chronoamperometry, and Tafel slope analysis. The Cu/PVdF-HFP fibrous catalysts exhibit significantly improved OER activity and durability compared with Cu plate as well as Cu-deposited PVdF-HFP with different microstructures. The unique fibrous structure provides better mass transport, diffusion, and large active surface area. In addition to the advantages of the fibrous structure, attenuated total reflection infrared (ATR-IR) and ex situ X-ray photoelectron spectroscopy revealed that the improved specific activity for Cu/PVdF-HFP fiber can be attributed to the synergistic effect between Cu and Cu/PVdF-HFP (electron transfer from Cu to PVdF-HFP) at the Cu|PVdF-HFP interface, which results in optimized reaction energetics for the OER.