Wang, TsingHaiTsingHaiWangChen, Ching-LungChing-LungChenKuan, Wei-FanWei-FanKuanLi, Wei-TongWei-TongLiKe, Ching-YaoChing-YaoKeLin, Tzu-HanTzu-HanLinCHUNG-YU GUANFuh, Huei-RuHuei-RuFuh2026-02-252026-02-252026-0309575820https://www.scopus.com/pages/publications/105028788311https://scholars.lib.ntu.edu.tw/handle/123456789/735981Article number 108519Understanding which structural and electronic descriptors primarily govern the photocatalytic reactivity of hematite remains challenging due to the complex interplay among lattice defects, band-structure modulation, and surface redox chemistry. This study aims to identify and quantitatively prioritize the key physicochemical factors that control hematite photocatalysis, rather than to determine a single optimal synthesis condition. Mn-doped hematite (α−Fe2O3) was selected as a model system and synthesized over varying Mn contents (up to 10 mol%) and calcination temperatures (400 −800 ℃). The materials were systematically characterized by XRD, Raman spectroscopy, XPS, and UV–vis analyses. Structure–property contour mapping was then integrated with Pearson correlation analysis to evaluate photocatalytic methylene blue degradation. Among all descriptors examined, band gap energy is identified as the strongest determinant of photocatalytic reactivity (r = −0.818, p < 0.001). The surface Fe(II)/Fe(III) ratio ranks as the second most influential factor (r = 0.555, p = 0.026), followed by the average lattice strain (r = −0.391, p = 0.134). These results indicate that electronic structure modulation and defect-related lattice distortion play more dominant roles than crystallite size or plane-specific strain. Contour analysis further reveals that pronounced band gap narrowing consistently occurs once Mn doping exceeds 5 mo% across all investigated calcination temperatures. In contrast, elevated surface Fe(II)/Fe(III) ratios emerge primarily under conditions combining both high Mn doping and high calcination temperature. These two descriptors therefore exhibit distinct but complementary statistical correlations with photocatalytic removal efficiency and apparent reaction kinetics. Rather than identifying a single optimal Mn content and calcination temperature, the statistical analysis highlight band gap narrowing and surface Fe redox state as the most transferable performance-governing descriptors. Collectively, this study establishes a descriptor-prioritization-based structure–activity framework, in which photocatalytic performance is most strongly associated with defect-mediated electronic structure modulation and surface Fe(III)/Fe(II) characteristics. This framework provides practical guidance for the rational design of hematite-based photocatalysts for low-carbon and sustainable wastewater treatment.falseBand gapHematitePhotocatalystStatistical correlation analysisSurface Fe(II)/Fe(III) ratiojournal article10.1016/j.psep.2026.1085192-s2.0-105028788311