MgO/N-doped carbon synthesized via facile NH3·H2O-modulated citric acid complexation for efficient room-temperature H2S oxidation

Carbon-based materials are widely used for H 2 S oxidation, yet their performance under ambient conditions requires further improvement via precise structural engineering. In particular, existing MgO-modified carbon materials still suffer from suboptimal H 2 S removal capacity, limited regenerability, and/or complicated synthesis processes, which restrict their practical application in room-temperature desulfurization. In this work, we report MgO/N-doped carbon catalysts synthesized by an NH 3 ·H 2 O-modulated citric acid complexation method, which demonstrated superior activity for ambient H 2 S oxidation. It was shown that the introduction of NH 3 ·H 2 O induced the formation of NH 4 NO 3 in pyrolysis precursors, and the decomposition of NH 4 NO 3 during pyrolysis created abundant carbon defects and also incorporated pyridinic/pyrrolic N species. These defects anchor Mg ions, leading to the formation of well-dispersed MgO nanosheets that enhanced surface basicity and facilitated H 2 S dissociation. Meanwhile, the defect-rich structure significantly improved O 2 activation to generate reactive 1 O 2 species for efficient H 2 S oxidation. The optimized MNC-3 delivered an exceptional H₂S capacity of 2.41 g/g cat. with 55 h breakthrough time at room temperature, and retained 0.78 g/g cat. after three regeneration cycles. This work provides a rational design strategy for high-performance, cost-effective room-temperature desulfurization materials through integrated modulation of active phase morphology, nitrogen doping, and carbon defects.