Carbon‐Layer Modulation of CoO <sub>x</sub> @C‐350 Nanoreactors Stabilizing Co <sup>0</sup> ‐Co <sup>2+</sup> Dual‐Active Site Ratio for High‐Efficiency Ambient‐Pressure Photothermal CO <sub>2</sub> Methanation
Xiaofang Shang, Yujie Gu, Yimeng Zhou, Zheng Lian, Mingyi Yu, Jie Ding, Qin Zhong
Abstract
Abstract The design of novel cobalt‐coated catalysts featuring synergistic dual‐active‐sites that facilitate coupled proton‐electron transfer has emerged as a pivotal strategy in ambient‐pressure photothermal catalysis. However, these catalysts often face the critical challenge of single active site deactivation under strong H 2 ‐reducing atmospheres. Herein, carbon‐coated CoO x @C‐x novel nanoreactors via a two‐step pyrolysis method is developed. The optimized CoO x @C‐350 demonstrates remarkable photothermal catalytic performance under light irradiation at 200 °C, achieving 96.15% CH 4 selectivity, 2.89 mmol·h −1 production rate, and 51.88% CO 2 conversion. In situ characterization and calculations reveal that dual‐site synergy enables coupling between Co 2+ ‐rich active domains and metallic Co, facilitating proton‐electron transfer to drive the formation of crucial * COOH intermediates. Notably, the outer carbon layer serves dual functions as both a photothermal conversion medium (generating localized heating) and a charge redistribution modulator for stabilizing Co 2+ species, establishing the cooperative mechanism of “Co 2+ /Co 0 dual‐active site synergy‐charge redistribution‐thermal localization”. Comparative studies demonstrate that CoO x @C‐230 (Co 3 O 4 ‐dominated) suffers from deactivation due to excessive hydrogen consumption by surface hydroxyl groups, while CoO x @C‐600 (Co 0 ‐enriched) shows limited CO 2 activation capability, highlighting that optimal valence control is critical. This work provides a novel paradigm for microenvironment engineering in photothermal synergistic catalysts.