高熵磷化物（HEPs）具有高度組成複雜性與潛在氧化還原的可調控性，但其於熱催化二氧化碳轉化中的效果尚未充分釐清。本研究以二氧化矽擔載之單金屬、三金屬與類高熵磷化物為觸媒，探討其於逆水煤氣轉化反應（RWGS）中的催化表現，並分析組成、結構與氧化還原行為對活性的影響。所有觸媒在RWGS反應中都僅生成一氧化碳，其中 FeCoNiPx/SiO2 表現最佳，在700°C下達51%二氧化碳轉化率，其表觀活化能為63.4 kJ mol⁻¹，低於 CrMnFeCoNiPx/SiO2 的75.6 kJ mol⁻¹。結構分析證實，FeCoNiPx/SiO2與CrMnFeCoNiPx/SiO2皆形成元素分布均勻之磷化物奈米顆粒，並於反應後維持結構穩定。XAS顯示Fe、Co、Ni與P物種可隨CO2 / H2 氣氛產生可逆的氧化還原變化，其中 FeCoNiPx/SiO2 具有更明顯的Ni氧化還原效應。結果指出，高熵效應可提升磷化物觸媒的結構穩定性與一氧化碳選擇性，但並不必然提升其RWGS活性。相較之下，催化性能主要受具可逆氧化還原能力的金屬磷化物位點所控制，其中FeCoNiPx/SiO2相較於CrMnFeCoNiPx/SiO2提供了更有利的Ni–P氧化還原活性界面。

In this study, silica-supported mono-metal, tri-metal, and high-entropy-composition phosphide catalysts were examined for the reverse water-gas shift (RWGS) reaction to clarify how phosphide structure and redox chemistry govern catalytic performance. FeCoNiPx/SiO2 showed 51% CO2 conversion at 700 oC and an apparent activation energy of 63.4 kJ mol−1, lower than that of CrMnFeCoNiPx/SiO2 at 75.6 kJ mol−1. X-ray absorption (XAS) analysis revealed that Fe, Co, and Ni species in FeCoNiPx/SiO2 and CrMnFeCoNiPx/SiO2 underwent reversible oxidation under CO2 and reduction under H2, whereas Ni in CrMnFeCoNiPx/SiO2 was less redox-responsive. P K-edge XAS further showed partial phosphide-to-phosphate transformation under CO2 and recovery under H2, indicating that both metal and phosphorus species participate in the redox cycle. These results show that high entropy composition can provide stable and selective RWGS catalysts but does not necessarily enhance activity. Instead, RWGS performance is governed by reversible metal-phosphide redox ensembles, with FeCoNiPx/SiO2 providing a more favorable balance than CrMnFeCoNiPx/SiO2.

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