Electrochemical water splitting is promising for utilizing intermittent renewable energy. The sluggish kinetics of the oxygen evolution reaction (OER), however, is a bottleneck in obtaining high efficiency. Only a few OER electrocatalysts have been developed for the use in acidic media despite the importance of a proton exchange membrane (PEM) water electrolyzer. IrO 2 is the only material that is both active and stable for the OER in highly corrosive acidic conditions. Herein, a facile and scalable synthesis of ultrathin IrO 2 nanoneedles is reported with a diameter of 2 nm using a modified molten salt method. The activity and durability for the OER are significantly enhanced on the ultrathin IrO 2 nanoneedles, compared to conventional nanoparticles. The ultrathin nanoneedles are successfully introduced to a PEM electrolyzer single cell with the enhanced cell performance.The ORCID identification number(s) for the author(s) of this article can be found under https://doi.

Minimizing the use of Pt catalysts in proton exchange membrane fuel cells (PEMFC) is important, considering its high price and scarcity. Herein, we demonstrate novel catalysts for PEMFCs with exceptionally...

Determination of the electrochemically active surface area (ECSA) is essential in electrocatalysis to provide surface normalized intrinsic catalytic activity. Conventionally, ECSAs of metal oxides and hydroxides are estimated using double layer capacitance (C dl ) measured at nonfaradaic potential windows. However, in the case of Ni-based hydroxide catalysts for the oxygen evolution reaction (OER), the nonfaradaic potential region before the Ni(II) oxidation peak is nonconductive, which hinders accurate electrochemical measurements. To overcome this problem, in this work, we have investigated the use of electrochemical impedance spectroscopy (EIS) at reactive OER potentials to extract the capacitance that is hypothesized to arise due to reactive OER intermediates (O*, OH*, OOH*) adsorbed on the catalyst surface. This allowed the estimation of ECSA and intrinsic activity of NiFe layered double hydroxide (NiFe LDH), the most active, state-of-the-art OER electrocatalyst in alkaline media. We analyzed the OER adsorbates capacitance (C a ) on NiFe LDH and Ni(OH) 2 at different electrode potentials and identified a suitable potential range for accurate ECSA evaluation. Finally, we validated our method and the choice of potential range through rigorous catalyst loading and support studies.

Productivity of formates from electrochemical CO2 reduction was enhanced by using a Sn catalyst with dense tips electrodeposited on a gas diffusion electrode.

Much effort has been devoted to developing electrocatalysts applicable to anion exchange membrane water electrolyzers (AEMWEs). Among many candidates for oxygen evolution reaction, NiFe-layered double hydroxide (LDH)-based electrocatalysts show the highest activity in an alkaline medium. Unfortunately, the poor electrical conductivity of NiFe-LDH limits its potential as an electrocatalyst, which was often solved by hybridization with conductive carbonaceous materials. However, we find that using carbonaceous materials for anodes has detrimental effects on the stability of AEMWEs at industrially relevant current densities. In this work, a facile monolayer structuring is suggested to overcome low electrical conductivity and improve mass transport without using carbonaceous materials. The monolayer NiFe-LDH deposited on Ni foam showed much better AEMWE performance than conventional bulk NiFe-LDH due to better electrical conductivity and higher hydrophilicity. A high energy conversion efficiency of 72.6% and outstanding stability at a current density of 1 A cm −2 over 50 h could be achieved without carbonaceous material. This work highlights electrical conductivity and hydrophilicity of catalysts in membrane-electrode-assembly as key factors for high-performance AEMWEs.