Pluronic-123 Assisted Synthesis of Cobalt Vanadate Microparticles (μ-CoV MPs) for Durable Electrochemical Oxygen Evolution Reaction in Seawater and Connate Water

Exploring different catalytic material paradigms could drive the search for the best oxygen evolution reaction (OER) catalyst to achieve industrially-feasible hydrogen fuel from water. Cobalt-based materials are considered good choices in this regard. Herein, we synthesized Pluronic-123 (P-123)-stabilized, unique, rough, globular-shaped cobalt vanadate microparticles (mu-CoV MPs) using an ultrasonic-assisted solvothermal method. The as-synthesized mu-CoV MPs were subjected to high-temperature annealing to improve the crystallinity and the surface polymer moieties were pyrolyzed. Conventional SEM, XRD, FTIR, and BET analyses evaluated the morphological and structural features. The temperature-controlled crystalline phase led to extensive OER performance in SW electrolytes. The OER onset potential (V-OER) was observed at 1.557 V@10 mA/cm(2) in seawater (SW) for mu-CoV MPs annealed at 400 degrees C compared to the V-OER of 1.632 V of non-annealed mu-CoV MPs. The current density showed a steep increase beyond 1.557 V, confirming the excellent electrokinetics OER behavior of the mu-CoV MPs-deposited electrode. The chronoamperometric (I-t) OER stability comparison in SW and connate water (CW) electrolytes indicated only a <20% initial current density decrease after 8 h in the case of the SW electrolyte. However, the CW electrolyte posed serious challenges to the electrode and activity was completely lost after <2 h. The electrolytic comparison indicated that SW is highly suitable for mu-CoV MPs electrodes.

Automated summary

Exploring different catalytic material paradigms is important for finding the best OER catalyst to produce hydrogen fuel from water. Cobalt-based materials, specifically the mu-CoV MPs synthesized in this study, show promising performance in seawater electrolytes. The annealing process significantly improves the crystallinity of the mu-CoV MPs, leading to enhanced OER behavior. However, the mu-CoV MPs electrode is not stable in connate water electrolytes.