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 (E_1/2 = 0.85 V and E_onset = 1.00 V), OER (E_j=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.

Hafnia-based thin films exhibit unconventional ferroelectricity. These materials also show rich polymorphism, and thus temperature and field-driven phase transitions, as well as oxygen migration. In a bigger context of exploring the synergy between ferroelectricity and diffusion-based structural phenomena, here we study temperature-dependent phase transitions in epitaxial Hf0.5Zr0.5O2(HZO)/La0.67Sr0.33MnO3 (LSMO, bottom electrode) heterostructures. We report topotactic phase transitions and their clear pathways in both LSMO and HZO layers upon heating under vacuum, using in situ scanning transmission electron microscopy (STEM). Specifically, we directly image oxygen and cationic columns using integrated differential phase contrast STEM and follow their evolution with temperature. We also perform in situ high temperature X-ray diffraction in air and show that the LSMO layer undergoes reversible thermal expansion and contraction when heated up to 850 °C, whereas HZO undergoes strain relaxation beyond 750 °C without any reversible phase transition. Our results provide a comprehensive and direct understanding of temperature-dependent structure, defect, and property correlations in these systems.