Ultra-stable and poison tolerance oxygen evolution activity enabled by surface In2O3-x(OH)y of Co3In2S2 large single-crystal

Abstract

Water is an earth-abundant source for clean hydrogen production via electrochemical water electrolysis (WE). However, the surface poisoning that occurs in aqueous electrolytes drastically deactivates the electrocatalytic performance of electrodes. Here, we report an electrochemically formed In2O3-x(OH)y on the surface of a large (1–1.5 mm long, 0.5–0.6 mm wide and 0.3–0.5 mm thick) single-crystal of Weyl semimetal Co3In2S2 (Co3In2S2/In2O3-x(OH)y) as an ultra-stable and poison tolerance electrode for the oxygen evolution reaction (OER) in 1 M KOH, addressing a bottleneck in WE. The OER activity of powder form of Co3In2S2 is limited by its aerophilic nature. Remarkably, the single-crystal electrodes maintained their high activity for a continuous operational period of 5 h in 1 M KOH electrolyte with/without 10 mM of strong surface-poisoning ligands i.e., potassium cyanide, bipyridine, and ethylenediaminetetraacetate disodium salt. The electrodes exhibited stable OER activity for 1000 h at 100 mA cm−2 (1.73 V vs. RHE). The temperature-dependent OER polarization curves (10–70 °C) unambiguously revealed surface poisoning through the suppression of precatalytic Co-redox peaks on the bipyridine poisoned electrode and lead to the stabilization of surface Co-sites. The X-ray photoelectron spectroscopy analyses of pristine, poisoned and post-electrocatalytic single-crystal Co3In2S2 electrodes revealed the existence of In2O3-x(OH)y surface phase, which could be the potential heterostructure for the origin of ultra-stable and poison tolerance OER activity.