Mechanistic Insights into S-Doped g-C₃N₄ for Enhanced Photocatalytic Performance: A Theoretical Study

Abstract

Non-metal doping is an effective strategy to modulate the electronic structure of graphitic carbon nitride (g-C₃N₄) and optimize its photocatalytic activity. Based on first-principles density functional theory, this work calculated the formation energy, electronic properties, and optical performance of S-doped monolayer g-C₃N₄. The results demonstrate that S atoms preferentially occupy interstitial sites, as characterized by low formation energy and thermodynamic spontaneity, which leads to stabilization, followed by the edge N2-sites. After introducing S impurities via the N2 and interstitial doping sites, the band gap of g-C₃N₄ is narrowed from 2.63 eV (calculated by the HSE06 functional) to 2.35 eV (for N2-site doping) and 1.99 eV (for interstitial-site doping), respectively. Both C₃N₄-N2 and S-interstitial doping enhance the delocalization of the highest occupied molecular orbital and the lowest unoccupied molecular orbital. Specifically, interstitial S atoms act as “bridges” to connect adjacent structural units, significantly improving carrier mobility and facilitating the separation of photogenerated electron-hole pairs. Furthermore, S-interstitial doping reduces the work function of g-C₃N₄ from 4.16 eV to 3.64 eV, which strengthens visible light absorption. This work provides theoretical support for the design and preparation of non-metal-doped modified g-C₃N₄ photocatalysts.

Keywords

Sulfur doping / g-C₃N₄ / Photocatalytic mechanism / First-principles calculation / Doping site

References

[1] LiuJ, FuW, LiaoY, FanJ, XiangQJ. Mater. Sci. Technol., 2021, 91224.

[2] FengC, DengY, TangL, ZengG, WangJ, YuJ, LiuY, PengB, FengH, WangJAppl. Catal. B, 2018, 239525.

[3] HainerA S, HodginsJ S, SandreV, VallieresM, LanternaA E, ScaianoJ CACS Energy Lett., 2018, 3542.

[4] HossainA, BhagyaT C, MukhanovaE A, SoldatovA V, HenaishA M A, MaoY, ShibliS M AAppl. Catal. B, 2024, 342123383.

[5] Ashu AbeyS, ReisN M, EmanuelssonE A C, ExpósitoA JChem. Eng. J., 2025, 519164951.

[6] MittalD, DuttaD PJ. Mater. Sci..Mater. Electron., 2021, 3218512.

[7] LiX, LinH, JiaX, ChenS, CaoJChin. J. Catal., 2025, 73205.

[8] HumayunM, HuZ, KhanA, ChengW, YuanY, ZhengZ, FuQ, LuoWJ. Hazard. Mater., 2019, 364635.

[9] KresseG, FurthmüllerJComput. Mater. Sci., 1996, 615.

[10] YeS, WangR, WuM-Z, YuanY-PAppl. Surf. Sci., 2015, 35815.

[11] LiuZ, ZhangY, WuY, YangB, ZhouZ, JinZJ. Mater. Sci. Technol., 2025, 23348.

[12] CaiY, FangM, XuY, WakeelM, HuB, WangXChem. Eng. J., 2025, 518164670.

[13] IsmailA, ZahidM, AhmadB, HayatS, AliS, BakhtiarS U H, AlodhaybA N, WuX, AlamQ, AliS, QiaoLChem. Eng. J., 2025, 513163023.

[14] JasniN, IqbalA, Norazmi AhmadM, PauziH, HussainM HMater. Today: Proc., 2022, 571154

[15] HussainA, MaqsoodS, JiR, ZhangQ, FarooqM U, BootaM, UmerM, HashimM, NaeemH, ToorZ S, AliA, HouJ, XueY, WangXDiamond Relat. Mater., 2023, 132109648.

[16] ChenD, YangJ, DingHAppl. Surf. Sci., 2017, 391384.

[17] LiZ, MaY, HuX, LiuE, FanJChin. J. Catal., 2019, 40434.

[18] TondaS, KumarS, KandulaS, ShankerVJ. Mater. Chem. A, 2014, 26772.

[19] HasijaV, RaizadaP, SudhaikA, SharmaK, KumarA, SinghP, JonnalagaddaS B, ThakurV KAppl. Mater. Today, 2019, 15494.

[20] ShahdustM, EsrafiliM D, VahedpourMChemistrySelect, 2025, 10e202405852.

[21] SagaraN, KamimuraS, TsubotaT, OhnoTAppl. Catal. B: Environ., 2016, 192193.

[22] LiY, WuS, HuangL, WangJ, XuH, LiHMater. Lett., 2014, 137281.

[23] GuoS, ZhuY, YanY, MinY, FanJ, XuQAppl. Catal. B: Environ., 2016, 185315.

[24] LiJ, ZhaoW, WangJ, SongS, WuX, ZhangGAppl. Surf. Sci., 2018, 45859.

[25] LiuM, JiaoY, QinJ, LiZ, WangJAppl. Surf. Sci., 2021, 541148558.

[26] LinY-R, DizonG V C, YamadaK, LiuC-Y, VenaultA, LinH-Y, YoshidaM, HuCJ. Colloid Interface Sci., 2020, 567202.

[27] XuQ, WangS, WangY, WuX, DaiJ, LiuJ, FangD, ZhangC, SunS, ChengT, YangH, XuG, RenX, KouJSep. Purif. Technol., 2025, 3671328885

[28] WangY, TianY, YanL, SuZJ. Phys. Chem. C, 2018, 1227712.

[29] ChangJ, ZhangT, QiuS, HuangN, PangD, LiH, MaseseT, ZhangH, LiZ, HuangZ DSmall, 2023, 192301579.

[30] KrokeEAngew. Chem. Int. Ed., 2014, 5311134.

[31] ZhuB, ZhangJ, JiangC, ChengB, YuJAppl. Catal. B: Environ., 2017, 20727.

[32] MaX, LvY, XuJ, LiuY, ZhangR, ZhuYJ. Phys. Chem. C, 2012, 11623485.

[33] WilliamsM JPolymers, 2023, 153870.

[34] WeiB, WangW, SunJ, MeiQ, AnZ, CaoH, HanD, XieJ, ZhanJ, HeMAppl. Surf. Sci., 2020, 511145549.

[35] CuiJ, LiangS, WangX, ZhangJMater. Chem. Phys., 2015, 161194.

[36] EmeryA A, WolvertonCScientific Data, 2017, 4170153.

[37] ZhouX, ChengY, XuX, ZhangL, TianS, XuX, GuoB, TangW, YanC, QianTInorg. Chem., 2025, 6414118.

[38] WangD, LeQ, ZhangW, NanZLangmuir, 2025, 4121144.

[39] ChavesA, AzadaniJ G, AlsalmanH, da CostaD R, FrisendaR, ChavesA J, SongS H, KimY D, HeD, ZhouJ, Castellanos-GomezA, PeetersF M, LiuZ, HinkleC L, OhS-H, YeP D, KoesterS J, LeeY H, AvourisP, WangX, LowTNPJ 2D Mater. Appl., 2020, 429.

[40] ZhangJ-Q, HuB, DongA, EglitisR I, YiZ-J, JiaRACS Appl. Nano Mater., 2023, 622506.

[41] LinY, ChenL, ZhangJ, GuiY, LiuLJ. Mater. Sci. Technol., 2024, 174218.

[42] OpokuF, GovenderK K, SittertC G C E V, GovenderP PAppl. Surf. Sci., 2018, 427487.

RIGHTS & PERMISSIONS

Jilin University, The Editorial Department of Chemical Research in Chinese Universities and Springer-Verlag GmbH