Synergistic Induction by Deep Eutectic Solvent and Carbon Dots for Rapid Construction of FeOOH Electrocatalysts Toward Efficient Oxygen Evolution Reaction

The development of efficient and stable oxygen evolution reaction (OER) electrocatalysts based on non-precious metals is pivotal for advancing sustainable energy conversion technologies. We present a facile and green strategy for synthesizing a high-performance HO-CDs-FeOOH/NF(D) composite catalyst by leveraging a synergistic system of FeCl3/urea deep eutectic solvent (DES) and hydroxyl-functionalized carbon dots (HO-CDs). This system orchestrates the rapid, in situ growth of FeOOH on nickel foam (NF) via simple immersion, wherein the DES acts as both an etchant and an iron source, while the HO-CDs induce a morphological transformation from sheet-like to granular stacking, thereby constructing highly active interfaces and increasing the density of accessible catalytic sites. The optimized catalyst exhibits exceptional OER performance, requiring an overpotential of only 251 mV to achieve 50 mA cm−2, with a Tafel slope of 55.4 mV dec−1. Moreover, it demonstrates outstanding stability, maintaining 98% of its initial current density after 24 h of continuous operation and showing negligible performance decay after 3000 cycles. This work presents a straightforward approach for designing high-performance Fe-based electrocatalysts through carbon dot-mediated morphology control via a facile DES-based impregnation strategy.