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<p>A new synthesis route for three-dimensional cage-type mesoporous carbon was developed using phosphoric acid (H<sub>3</sub>PO<sub>4</sub>) as a dual-function catalyst. H<sub>3</sub>PO<sub>4</sub> promoted dehydration of sucrose as an acid catalyst and enabled systematic tuning of both cage size and inter-cage window size by forming a polyphosphoric acid layer at the silica–carbon interface. By increasing the H<sub>3</sub>PO<sub>4</sub>/sucrose molar ratio, uniform mesopore diameters expanded from 13.1 to 16.6&#xa0;nm and window sizes from 7.3 to 9.8&#xa0;nm at a pyrolysis temperature of 900&#xa0;°C. In lithium-sulfur (Li–S) batteries, enlarged windows significantly improved lithium polysulfides (LiPSs) transport and rate capability. Notably, a well-preserved, template-replicated mesoporous framework was achieved even at an exceptionally low carbonization temperature of 400&#xa0;°C, whereas sulfuric-acid-derived samples exhibited poorly developed porosity and structural collapse under identical conditions. The cage-type mesoporous carbon synthesized at 400&#xa0;°C retained abundant oxygen- and phosphorus-containing polar functional groups, as confirmed by elemental analysis and XPS, leading to markedly enhanced LiPSs adsorption. Accordingly, the highly functionalized mesoporous carbon delivered superior cycling stability, maintaining 82.3% of its initial capacity after 300 cycles. Post-mortem XPS analysis further confirmed strong chemical interactions between LiPSs and surface functional groups. Importantly, H<sub>3</sub>PO<sub>4</sub> played a dual role as an acid catalyst and pore-structure modifier by forming a polyphosphoric acid layer at the silica–carbon interface. This layer stabilized the carbon precursor via strong polar–polar interactions, effectively suppressing pore collapse and mesopore merging. Such interfacial stabilization can provide a general strategy for the low-temperature fabrication of structurally robust mesoporous carbons.</p>

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Dual-function phosphoric acid strategy for synthesis of 3D cage-structured mesoporous carbons with tunable pore/window architectures toward high-performance lithium–sulfur batteries

  • 期刊论文

  • 发表日期：

    2026年5月21日

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  • Sun Hyu Kim,
  • Je Yeon Kim,
  • Hyung Ik Lee,
  • Yongwoo Lee,
  • Hye Ran Kim,
  • Kyoung Mun Kim,
  • Seok Kim,
  • Yongju Jung

摘要

A new synthesis route for three-dimensional cage-type mesoporous carbon was developed using phosphoric acid (H3PO4) as a dual-function catalyst. H3PO4 promoted dehydration of sucrose as an acid catalyst and enabled systematic tuning of both cage size and inter-cage window size by forming a polyphosphoric acid layer at the silica–carbon interface. By increasing the H3PO4/sucrose molar ratio, uniform mesopore diameters expanded from 13.1 to 16.6 nm and window sizes from 7.3 to 9.8 nm at a pyrolysis temperature of 900 °C. In lithium-sulfur (Li–S) batteries, enlarged windows significantly improved lithium polysulfides (LiPSs) transport and rate capability. Notably, a well-preserved, template-replicated mesoporous framework was achieved even at an exceptionally low carbonization temperature of 400 °C, whereas sulfuric-acid-derived samples exhibited poorly developed porosity and structural collapse under identical conditions. The cage-type mesoporous carbon synthesized at 400 °C retained abundant oxygen- and phosphorus-containing polar functional groups, as confirmed by elemental analysis and XPS, leading to markedly enhanced LiPSs adsorption. Accordingly, the highly functionalized mesoporous carbon delivered superior cycling stability, maintaining 82.3% of its initial capacity after 300 cycles. Post-mortem XPS analysis further confirmed strong chemical interactions between LiPSs and surface functional groups. Importantly, H3PO4 played a dual role as an acid catalyst and pore-structure modifier by forming a polyphosphoric acid layer at the silica–carbon interface. This layer stabilized the carbon precursor via strong polar–polar interactions, effectively suppressing pore collapse and mesopore merging. Such interfacial stabilization can provide a general strategy for the low-temperature fabrication of structurally robust mesoporous carbons.