Multiscale Engineering of Nonprecious Metal Electrocatalyst for Realizing Ultrastable Seawater Splitting in Weakly Alkaline Solution

Abstract

Seawater electrolysis is an attractive technique for mass production of high-purity hydrogen considering the abundance of seawater. Nevertheless, due to the complexity of seawater environment, efficient anode catalyst, that should be, cost effective, highly active for oxygen evolution reaction (OER) but negligible for Cl 2 /ClOformation, and robust toward chlorine corrosion, is urgently demanded for large-scale application. Although catalysis typically appears at surface, while the bulk properties and morphology structure also have a significant impact on the performance, thus requiring a systematic optimization. Herein, a multiscale engineering approach toward the development of cost-effective and robust OER electrocatalyst for operation in seawater is reported. Specifically, the engineering of hollow-sphere structure can facilitate the removal of gas product, while atom-level synergy between Co and Fe can promote Co sites transforming to active phase, and in situ transformation of sulfate ions layer protects catalysts from corrosion. As a result, the as-developed hollow-sphere structured CoFeS x electrocatalyst can stably operate at a high current density of 100 mA cm -2 in the alkaline simulated seawater (pH = 13) for 700 h and in a neutral seawater for 20 h without attenuation. It provides a new strategy for the development of electrocatalysts with a broader application potential.

High‐Valence‐Manganese Driven Strong Anchoring of Iridium Species for Robust Acidic Water Oxidation

“…The TOF values have been calculated for all the catalysts. [ 4,39 ] The TOF of Ir‐MnO 2 (160)‐CC reached up to 0.321 s −1 at the overpotential of 370 mV (vs RHE), remarkably higher than that of h‐IrO 2 ‐CC (0.01 s −1 ) and d‐IrO 2 ‐CC (0.005 s −1 ). The above results indicate that Ir‐MnO 2 (160)‐CC could serve as a promising OER electrocatalyst for water splitting in acidic media.…”

Designing electrocatalysts for seawater splitting: surface/interface engineering toward enhanced electrocatalytic performance

“…Oxidizing the doped S or P heteroatoms in catalysts reconstitutes a sulfate or phosphate passivation layer on the electrocatalyst surface, protecting the anode from Cl − /ClO − corrosion. 113,114 (d) Constructing buffer structures to mitigate the damage to the structure by Cl − invasion. Different from the above strategies, this actively dopes Cl − into the lattice to form chlorinated hydroxide to avoid the structural damage and deactivation of the catalyst caused by Cl − infiltration.…”

Recent advances in direct seawater splitting for producing hydrogen

“…32 Similarly, some oxygen-containing anions (such as PO 4 3− , SO 4 2− , and NO 3 − ) have also been reported to reduce the selectivity of anodic chlorine evolution. 13,32–35 For example, Dai et al synthesized a multilayer anode catalyst (NiFe/NiS x –Ni) with nickel–iron hydroxide uniformly coated on nickel sulfide on foam nickel (Fig. 4(d)).…”