Scalable Fabrication of Highly Active and Durable Membrane Electrodes toward Water Oxidation

Abstract

The electrocatalytic oxygen evolution reaction (OER) is a highly important reaction that requires a relatively high overpotential and determines the rate of water splitting—a process for producing hydrogen. The overall OER performance is often largely limited by uncontrollable interface when active catalysts are loaded on conductive supports, for which polymer binders are widely used, but inevitably block species transportation channels. Here, a scalable fabrication approach to freestanding graphitized carbon nanofiber networks is reported, which provides abundant sites for in situ growing Fe/Ni catalysts with the improved interface. The fabricated hybrid membrane exhibits high activity and durability toward OER, with an overpotential of 280 mV at a geometrical current density of 10 mA cm−2 and a Tafel slope of 30 mV dec−1 in alkaline medium. As implemented as a freestanding electrode, the 3D hybrid structure achieves further enhanced OER performance with an overpotential down to 215 mV at 10 mA cm−2. This work provides fresh insights into rationally fabricating OER electrocatalysts from the angle of electrode design.

The Effect of Heteroatom Doping on Nickel Cobalt Oxide Electrocatalysts for Oxygen Evolution and Reduction Reactions

“…Besides the ORR, the OER is the reverse reaction which, has been extensively studied for water splitting and metal-air batteries. [54,55] In the literature, several works describe the bifunctional catalysts with an efficient catalytic activity toward the ORR and OER. [56,57] The as-prepared nickel cobalt oxides electrocatalytic activity towards OER was evaluated in alkaline solution.…”

Electronic modulation and interface engineering of electrospun nanomaterials‐based electrocatalysts toward water splitting

“…In fact, to tune the OER performance, the interface between the active electrocatalyst and CNFs is very important 171‐198 . Li et al 197 developed an electrospinning and carbonization process to prepare CoFe 2 O 4 nanoparticles encapsulated in N‐doped CNFs (CoFe 2 O 4 /NCNFs) as an OER electrocatalsyt.…”

Fibrous‐Structured Freestanding Electrodes for Oxygen Electrocatalysis

“…[ 72 ] In addition, core–sheath nanofibers were prepared by photopolymerizing polythiophene on electrospun PAN/C 3 N 6 H 6 /FeCl 3 nanofibers, and subsequent stabilization and carbonization processes led to the formation of Fe‐S/N‐C catalyst, which exhibited an ORR onset potential of 0.94 V. [ 73 ] Using an in situ growth approach, Fe/Ni alloy nanosheets were first electrodeposited onto the surface of electrospun carbon nanofibers, then the composite structure was phosphatized at 300 °C with NaH 2 PO 2 (Figure 5d). [ 57 ] The SEM image in Figure 5e reveals that Fe/Ni/P ultrathin sheet arrays were uniformly and vertically grown on the nanofibers. The freestanding 3D electrode showed an OER overpotential as low as 215 mV at 10 mA cm −2 in 1 m KOH (Figure 5f).…”