Carbon Oxyanion Self‐Transformation on NiFe Oxalates Enables Long‐Term Ampere‐Level Current Density Seawater Oxidation

Abstract

Seawater electrolysis is an attractive way of making H2 in coastal areas, and NiFe‐based materials are among the top options for alkaline seawater oxidation (ASO). However, ample Cl− in seawater can severely corrode catalytic sites and lead to limited lifespans. Herein, we report that in situ carbon oxyanion self‐transformation (COST) from oxalate to carbonate on a monolithic NiFe oxalate micropillar electrode allows safeguard of high‐valence metal reaction sites in ASO. In situ/ex situ studies show that spontaneous, timely, and appropriate COST safeguards active sites against Cl− attack during ASO even at an ampere‐level current density (j). Our NiFe catalyst shows efficient and stable ASO performance, which requires an overpotential as low as 349 mV to attain a j of 1 A cm−2. Moreover, the NiFe catalyst with protective surface CO32− exhibits a slight activity degradation after 600 h of electrolysis under 1 A cm−2 in alkaline seawater. This work reports effective catalyst surface design concepts at the level of oxyanion self‐transformation, acting as a momentous step toward defending active sites in seawater‐to‐H2 conversion systems.

Insights on MOF-derived metal–carbon nanostructures for oxygen evolution

“…4 However, the effectiveness of water splitting is significantly hampered by the oxygen evolution reaction (OER), primarily due to its multi-step four-electron transfer pathway characterized by sluggish reaction kinetics. 5,6 Although numerous effort has been devoted into developing OER catalysts, 7–11 there is a critical need for superior and stable OER catalysts.…”

Spin configuration modulation of Co3O4 by Ru doping for boosting the overall water splitting and hydrazine oxidation reactions

“…Among the hydrogen production technologies reported, electrocatalytic water splitting powered by the renewable electricity from intermittent energy (such as wind and solar energy) is regarded as an appealing route with the merits of zero-carbon emission and high-purity products, which consists of the cathodic hydrogen evolution reaction (HER) and the anodic oxygen evolution reaction (OER). 4–9 However, the intrinsic sluggish kinetics and large kinetic barrier of the OER as a major bottleneck seriously impede the efficiency of overall water splitting (OWS), owing to the complex four electron-transfer steps. At present, Pt-based materials and Ru/Ir-based oxides are acknowledged as state-of-the-art HER and OER electrocatalysts, respectively.…”

Three-dimensional porous NiCoP foam enabled high-performance overall seawater splitting at high current density

“…3–7 Particularly, given the abundant availability of seawater on earth, direct electrolysis of seawater has garnered increasing attention for large-scale H 2 production, but the high concentrations of the chloride anion (Cl − ) in seawater can lead to the undesirable chloride evolution reaction competing with anodic OER and even continuously corrode the electrode, which greatly restricts the development of seawater splitting technology. 8–17 Using a bifunctional water-splitting electrocatalyst operating efficiently for both the OER and HER has advantages of simplifying the system and lowering the cost. 18 As such, it is of great importance to develop high-activity, robust, and non-precious bifunctional electrocatalysts for overall seawater splitting in the same electrolyte.…”