近數十年來隨著溫室氣體排放量增加導致的全球暖化問題，如何有效轉化大氣中的二氧化碳成為重要的研究主題。二氧化碳氫化反應作為一種具應用前景的碳捕捉與再利用技術，可助於實現碳循環及能源再利用，具備綠色化學的理念。異相催化劑的使用有助於該反應的進行，而活性常受到金屬載體交互作用的影響。然而金屬前驅物與金屬氧化物載體之間的交互作用，以及其在熱活化後對催化劑活性的影響，是一個十分重要但過去尚未被充分研究的課題。本研究探討了二氧化矽與多種鈷前驅物（包括硝酸鈷、氯化鈷和氯化三(乙二胺)合鈷(III)）之間的交互作用，以及交互作用對於逆水煤氣轉換反應（RWGS）催化活性的影響。 透過漫反射紫外—可見光光譜（Diffuse reflectance UV–Vis spectroscopy）、傅立葉轉換紅外光光譜（FT–IR spectroscopy）、Ninhydrin試劑定性分析以及與 pH值相關的表面結合實驗，推論鈷六水合陽離子（[CoH2O6]2+）會與單個表面去質子化的矽醇基（silanol group）進行內球螯合 (inner–sphere complexation）；相對地，三(乙二胺)鈷(III)陽離子（[Co(en)3]3+）則透過氫鍵與表面去質子化的矽醇基產生外球螯合 (outer–sphere complexation)。催化劑表面鑑定結果顯示，在熱活化後，以內球配位的[CoH2O6]2+會在二氧化矽表面形成微小的 Co3O4 奈米顆粒。這些奈米顆粒（粒徑約 4.6 nm）在 RWGS 反應中展現出顯著更高的CO2轉化率，同時能保持接近 100 % 的 CO 選擇性。相反地，經由氫鍵結合的 [Co(en)3]3+ 在鍛燒後則可能轉化為四面體配位的類矽酸鈷物種，導致催化劑於RWGS反應中的活性較低。 本研究表明前驅物與載體之間不同的交互作用模式，會導致熱處理後二氧化矽表面上的鈷物種呈現出不同的化學狀態，最終造成了催化劑於RWGS 反應中催化活性的顯著差異。;In recent decades， with global warming exacerbated by increasing greenhouse gas emissions， the effective conversion of atmospheric CO2 has emerged as a crucial research topic. As a promising carbon capture and utilization (CCU) technology， CO2 hydrogenation contributes to achieving a closed carbon cycle and energy recycling， embodying the principles of green chemistry. The employment of heterogeneous catalysts facilitates this reaction， where the catalytic activity is frequently influenced by metal—support interactions (MSI). However， the interaction between metal precursors and metal oxide supports， and its influence on catalyst activity after thermal activation， is an important yet under-investigated subject. This research studied the interaction between SiO2 and various Co-based precursors， including cobalt nitrate， cobalt chloride， and Tris(ethylenediamine)cobalt (III) chloride and the implication on the activity of reverse water-gas-shift reaction (RWGS). Through Diffuse reflectance UV-Vis ， FT–IR spectroscopy， Ninhydrin test and pH–dependent surface binding experiments， we deduce that the cobalt hexahydrate cation ([Co(H2O)6]2+) coordinates with a single surface deprotonated silanol group (inner–sphere complexation)， whereas the tris(ethylenediamine)cobalt(III) cation ([Co(en)3]3+) likely interacts with surface deprotonated silanol groups via hydrogen bonding (outer–sphere complexation). After thermal activation， surface characterizations suggested that the inner–sphere coordinated [Co(H2O)6]2+ leads to the formation of small Co3O4 nanoparticles on the silica surface. These nanoparticles (~ 4.6 nm) exhibited significantly higher CO2 conversion in the RWGS reaction while maintaining nearly 100% CO selectivity. By contrast， the hydrogen-bonded [Co(en)3]3+ leads to the formation of tetrahedral coordinated cobalt silicate-like species after calcination， resulting in lower activity in the RWGS reaction. Our study demonstrates that the varying modes of precursor—support interaction lead to distinct chemical states of the cobalt species on the silica surface after thermal treatment， which ultimately dictates the differences in catalytic activity in RWGS reaction.
