Template-Assisted Mechanosynthesis Leading to Benchmark Energy Efficiency and Sustainability in the Production of Bifunctional Fe–N–C Electrocatalysts

Efficient and sustainable synthesis of performant metal/nitrogen-doped carbon (M–N–C) catalysts for oxygen reduction and evolution reactions (ORR/OER) is vital for the global switch to green energy technologies–fuel cells and metal–air batteries. This study reports a solid-phase template-assisted mechanosynthesis of Fe–N–C, featuring low-cost and sustainable FeCl3, 2,4,6-tri(2-pyridyl)-1,3,5-triazine (TPTZ), and NaCl. A NaCl-templated Fe-TPTZ metal–organic material was formed using facile liquid-assisted grinding/compression. With NaCl, the Fe-TPTZ template-induced stability allows for a rapid, thus, energy-efficient pyrolysis. Among the produced materials, 3D-FeNC-LAG exhibits remarkable performance in ORR (E1/2 = 0.85 V and Eonset = 1.00 V), OER (Ej=10 = 1.73 V), and in the zinc–air battery test (power density of 139 mW cm–2). The multilayer stream mapping (MSM) framework is presented as a tool for creating a sustainability assessment protocol for the catalyst production process. MSM employs time, cost, resource, and energy efficiency as technoeconomic sustainability metrics to assess the potential upstream impact. MSM analysis shows that the 3D-FeNC-LAG synthesis exhibits 90% overall process efficiency and 97.67% cost efficiency. The proposed synthetic protocol requires 2 times less processing time and 3 times less energy without compromising the catalyst efficiency, superior to the most advanced methods.