Integration of pentagonal defects and non-metal heteroatoms in carbon matrix for anchoring Ru nanoparticles towards efficient hydrazine oxidation-assisted hydrogen evolution

Ru nanoparticles anchored on a heteroatom-doped carbon matrix enriched in pentagonal defects are prepared. • Synergy of pentagonal defects and heteroatoms tunes Ru electronic structure for HzOR and HER. • Ru on S-doped carbon enriched in pentagonal defects delivers superior HER and HzOR activity, surpassing Pt/C. • HzOR-assisted HER system needs only 0.485 V to reach 1 A cm −2 in a flow electrolyzer. Replacing the anodic oxygen evolution reaction with the hydrazine oxidation reaction (HzOR) enables energy-saving hydrogen production but demands efficient bifunctional electrocatalysts. Herein, an electrocatalyst based on ruthenium nanoparticles (Ru NPs) anchored on a uniquely engineered carbon matrix that integrates pentagonal defects and non-metal heteroatoms (Ru/PDXC, X = S, N or P) is designed. Through the synergistic coupling of pentagonal defects and non-metal heteroatoms, the electronic structure of Ru NPs is tailored, thereby enabling modulation of the adsorption energetics of key intermediates for both HzOR and hydrogen evolution reaction (HER). The synthesized Ru/PDSC catalyst delivers outstanding bifunctional activity, requiring a working potential of −70 mV for HzOR and an overpotential of 17 mV for HER to reach a current density of 10 mA cm −2 , outperforming commercial Pt/C. In a two-electrode HzOR-assisted HER system, a low cell voltage of 28 mV is sufficient to achieve a current density of 10 mA cm −2 . Moreover, the flow electrolyzer yields an industrially relevant current density of 1 A cm −2 , requiring a cell voltage of just 0.485 V. This study contributes a fundamental insight for the design and synthesis of advanced bifunctional Ru-based electrocatalysts by engineering the pentagonal defects and non-metal heteroatoms of a carbon matrix. Download: Download high-res image (458KB) Download: Download full-size image