Bimetallic Transition Metal-Supported Biomass-Derived Carbon Catalyst for Efficient Hydrazine Oxidation

Direct hydrazine fuel cells (DHFCs) have attracted significant interest as a promising method for sustainable hydrogen production, as they can overcome the slow oxygen evolution rate that limits conventional water splitting. The practical deployment of DHFCs is strongly dependent on the availability of cost-effective and efficient anode electrocatalysts for the hydrazine oxidation reaction (HzOR). The current study proposes a straightforward, scalable, and ecologically sustainable approach to the synthesis of non-noble metal electrocatalysts derived from sustainable biomass resources. The synthesis of nitrogen-doped carbon (N–C) was achieved through a hydrothermal carbonisation (HTC) process, utilising birchwood chips. This was followed by activation and nitrogen incorporation, yielding a porous, conductive carbon framework. Subsequently, iron (Fe) and manganese–iron (MnFe) were introduced as active components. The morphology, structure, and elemental composition of the MnFe, MnFe/N–C, and Fe/N–C catalysts were characterised by scanning electron microscopy (SEM), X-ray diffraction (XRD), and energy-dispersive X-ray spectroscopy (EDS). The catalytic activity of the catalysts for HzOR was evaluated in an alkaline medium by performing cyclic voltammetry (CV).

Electrochemical investigations have demonstrated that the MnFe/N–C catalyst demonstrates a significantly enhanced HzOR activity, exhibiting a lower onset potential and a substantially higher current density in comparison with both Fe/N–C and MnFe counterparts. The enhanced electrocatalytic performance of MnFe/N–C is attributable to a combination of factors, including the presence of numerous exposed active sites, the optimised mass transport within the porous nitrogen-doped carbon matrix, and the robust synergistic interactions between Mn, Fe, and N–C. The results of this study identify MnFe/N–C as a highly promising anode material for DHFCs. This work offers a viable, cost-effective, and sustainable approach to the design of efficient electrocatalysts that do not utilise noble metals. It provides significant insights into the development of next-generation hydrazine-based energy conversion and hydrogen production technologies.

Acknowledgment

This research was funded by a grant (No. P-ST-23-310) from the Research Council of Lithuania.