Substrate-free growth of N-doped bamboo tube morphology on CoNi alloy nanoparticles as an electrocatalyst for anion exchange membrane fuel cells

Abstract

In the realm of fuel cell technology, the quest for durable and economical electrocatalysts persists as a critical endeavour. Herein, we introduce a durable electrocatalyst boasting a resilient knotted bamboo tube-like morphology, termed the “tip-in growth”, achieved through a single-step synergistic catalytic pyrolysis method. The innovative approach involves the diffusion of carbon atoms on CoNi-alloy nanoparticles, resulting in nitrogen-doped bamboo-like carbon tubes encapsulating CoNi-alloy nanoparticles (CoNi@NC-T). Notably, this architecture not only fosters ample cavities for facilitating induced current generation but also induces a non-uniform distribution of local charges due to nitrogen doping, thereby enhancing conduction and polarization. Furthermore, the confinement of the CoNi-alloy within the carbon tubes effectively prevents nanoparticle aggregation and shields the alloy from corrosion, ensuring stable performance even in harsh chemical environments. Our study delves into the intricate interplay of temperature, thermal polymerization of dicyandiamide and the catalytic role of CoNi-alloy nanoparticles in shaping the derived morphology, elucidated through meticulous replication of reaction conditions via thermo-gravimetric analysis (TG-DSC). Remarkably, CoNi@NC-T exhibits activity on par with that of the state-of-the-art Pt/C catalyst for the oxygen reduction reaction (ORR) and demonstrates unparalleled robustness, evidenced by a minimal shift in the E_1/2 value after extensive 30 000 potential cycles. Corroborating its durability, Fe-SEM analysis confirms the retention of the bamboo-tube morphology post-cycling. CoNi@NC-T, as a cathode catalyst in an anion exchange membrane fuel cell (AEMFC), has delivered a peak power density of 170 mW cm⁻² with a FUMASEP® FAA-3-30 membrane underscoring its potential for practical AEMFC application.