Pressure-mediated crystalline g-C$_3$N$_4$ with enhanced spatial charge transport for solar H$_2$ evolution and photocathodic protection of 304 stainless steels
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| Format: | Preprint |
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2025
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| _version_ | 1866915408945086464 |
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| author | Gao, Xiaochun Hou, Shaoqi Su, Dawei |
| author_facet | Gao, Xiaochun Hou, Shaoqi Su, Dawei |
| contents | Conjugated polymeric g-C$_3$N$_4$ has emerged as a leading semiconductor for solar-to-chemical energy conversion due to its unique electronic band structure, robust physicochemical stability, and environmental benignity. However, defect engineering-while effective at enhancing visible-light absorption and charge separation-often introduces excessive dangling bonds and lattice disorder, which exacerbate carrier recombination and impair light harvesting. High crystallinity offers a complementary route to improve spatial charge transport, yet strategies that concurrently optimize crystallinity and surface defects remain underexplored. Here we report a pressure-mediated ion thermal synthesis of high-crystalline g-C$_3$N$_4$ (CCN-P) using a NaCl/KCl eutectic salt under elevated pressure. The molten salt facilitates in-plane and cross-plane crystal growth, while applied pressure reduces interlayer spacing and shortens photocarrier pathways. This dual modulation yields CCN-P with balanced surface defects (-CN and -NHx), an electron-trapping resistance (Rtrap) of 11.36 k$Ω$ cm$^2$ and a photocarrier decay rate constant of 0.013 s$^{-1}$. CCN-P achieves a hydrogen evolution rate of 2168.8 $μ$mol g$^{-1}$ h$^{-1}$ and delivers 78.5% dark photocathodic protection of 304 stainless steel over 7500 s, outperforming bulk and conventionally crystalline g-C$_3$N$_4$. This straightforward pressure-ion thermal approach provides a versatile platform for tailoring crystalline frameworks and defect distributions in polymeric semiconductors for efficient solar energy conversion. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2507_18914 |
| institution | arXiv |
| publishDate | 2025 |
| record_format | arxiv |
| spellingShingle | Pressure-mediated crystalline g-C$_3$N$_4$ with enhanced spatial charge transport for solar H$_2$ evolution and photocathodic protection of 304 stainless steels Gao, Xiaochun Hou, Shaoqi Su, Dawei Materials Science Conjugated polymeric g-C$_3$N$_4$ has emerged as a leading semiconductor for solar-to-chemical energy conversion due to its unique electronic band structure, robust physicochemical stability, and environmental benignity. However, defect engineering-while effective at enhancing visible-light absorption and charge separation-often introduces excessive dangling bonds and lattice disorder, which exacerbate carrier recombination and impair light harvesting. High crystallinity offers a complementary route to improve spatial charge transport, yet strategies that concurrently optimize crystallinity and surface defects remain underexplored. Here we report a pressure-mediated ion thermal synthesis of high-crystalline g-C$_3$N$_4$ (CCN-P) using a NaCl/KCl eutectic salt under elevated pressure. The molten salt facilitates in-plane and cross-plane crystal growth, while applied pressure reduces interlayer spacing and shortens photocarrier pathways. This dual modulation yields CCN-P with balanced surface defects (-CN and -NHx), an electron-trapping resistance (Rtrap) of 11.36 k$Ω$ cm$^2$ and a photocarrier decay rate constant of 0.013 s$^{-1}$. CCN-P achieves a hydrogen evolution rate of 2168.8 $μ$mol g$^{-1}$ h$^{-1}$ and delivers 78.5% dark photocathodic protection of 304 stainless steel over 7500 s, outperforming bulk and conventionally crystalline g-C$_3$N$_4$. This straightforward pressure-ion thermal approach provides a versatile platform for tailoring crystalline frameworks and defect distributions in polymeric semiconductors for efficient solar energy conversion. |
| title | Pressure-mediated crystalline g-C$_3$N$_4$ with enhanced spatial charge transport for solar H$_2$ evolution and photocathodic protection of 304 stainless steels |
| topic | Materials Science |
| url | https://arxiv.org/abs/2507.18914 |