Green Lysine-Doped Lignin-Derived Carbon Dots Stabilize Ru Nanoclusters for Efficient Water Splitting

Abstract Developing sustainable Ru-based electrocatalysts for water splitting is promising but limited by Ru aggregation and weak interfacial stabilization. Herein, we present a green co-construction strategy to fabricate highly dispersed Ru nanoclusters using lysine-doped lignin-derived carbon dots (Lys-LCDs) as multifunctional supports. The carbon dots provide an aromatic framework with abundant vacancies, while lysine introduces N/O coordination sites to regulate Ru nucleation. Among tested amino acids, lysine yielded the highest carbon-dot production and was selected for catalyst construction. After thermal activation, Ru@Lys-LCDs-600 °C exhibits excellent bifunctional activity in 1 M KOH, requiring overpotentials of 30 mV for HER and 130 mV for OER at 10 mA cm–2. It also shows a low Tafel slope (61.3 mV dec–1), small charge-transfer resistance (0.83 Ω), and stable performance over 3000 cycles. For overall water splitting, it delivers 1.47 V at 10 mA cm–2, with only a 34 mV increase after 250 h. DFT calculations reveal that vacancies and lysine-derived coordination sites enhance Ru anchoring, suppress aggregation, stabilize highly dispersed Ru nanoclusters, and reduce their tendency toward excessive aggregation and growth. This work offers a sustainable route to high-performance Ru-based electrocatalysts.