Phase Junction Induction Through Atomic Ratio Tuning of Molybdenum Carbides for Enhanced Stepwise Iodine Conversion

Abstract

Iodine redox conversion often suffers from polyiodide formation and deactivation due to the shuttle effect. To address these challenges, the atomic ratio of molybdenum carbide (Mo_xC) nanoclusters are modulated, uniformly dispersed within nitrogen-doped carbon, to induce distinct phase-junctions through a flash Joule heating method. This strategy not only physically traps iodine within porous carbon but also strengthens chemisorption by forming Mo_xC phase junctions, facilitating efficient iodine conversion. The resulting built-in electric field accelerates charge migration, promoting the reduction of polyiodides to iodide ions and enhancing overall electrocatalysis. Spectroscopic analysis reveals minimal intermediate species, indicative of rapid iodine redox kinetics with low energy barriers confirmed by theoretical calculations. Consequently, zinc-iodine batteries exhibit a remarkable lifespan of over 50 000 cycles with a capacity retention of 95.2%. This phase-junction engineering ensures the synergistic effect that accelerates charge migration and electrocatalysis, offering valuable insights to design advanced catalysts for zinc-iodine batteries and beyond.