隨著綠色能源日益被重視，具潔淨無汙染優勢的氫能之重要性被寄予厚望，各國爭相發展並投入大量技術以達成零碳排。而氫氣的產出有許多方式，其中又以光電化學水分解產氫最具有前瞻性，此為利用太陽光照射並施加微小偏壓使水分解出氫氣之技術，可直接將太陽的能量轉換成氫氣進行儲存，在光能的輔助下，不須消耗過多的能量，具有節省能源的優勢。然而光電化學水解產氫仍面臨低載子分離效率、載子介面傳輸速率緩慢及可見光吸收效果較差等因素而限制其發展。因此本研究以FeOOH奈米顆粒對WO3奈米片進行表面修飾來增加其在可見光波段的吸收，並結合氬氣電漿進行表面處理，使試片表面之氧空缺比例從原來的7.3 %提高至34.5 %，此舉有助於加速載子介面之反應速率及幫助電洞傳遞。而後，進一步加入碳量子點( CQDs )來增加有效電化學活性表面積。綜合以上方式，本研究成功製備出CQDs / Ar plasma treated FeOOH @WO3 NPs薄膜，並透過能帶結構的建立，證實材料間之協同作用有助於提升載子分離效率。最終，此複合結構薄膜於光電特性表現上，其光電流密度及有效電化學活性表面積可分別達到2.18 mA /cm2及751 μF∙cm-2，相較於純WO3奈米片，光電流密度提升將近3.5倍，且開路電位降低至425 mV，往負偏壓偏移了257 mV，展現優異光電性質。
於機制探討，本研究以UV-vis說明FeOOH@WO3 NPs在可見光波段吸收的提升；並利用XPS研究FeOOH@WO3 NPs表面氧空缺及Fe2+/ Fe3+元素價態比例的改變；亦透過XRD探討FeOOH於不同浸泡時間下的結晶性變化；此外，藉由TEM來確認CQDs的平均粒徑以及複合結構間之界面；並以UPS探討氬電漿處理後材料與電解質介面能帶彎曲的程度。最終本研究成功建構出CQDs / Ar plasma treated FeOOH @WO3 NPs所形成的三元能帶結構，並證明其擁有優異的光電特性及產氫效率，而未來將持續發展相對應產氧技術並搭配本研究之產氫結構，更進一步結合儲氫科技建構出完整產氫鏈，以期達到永續發展之氫經濟社會。

Photoelectrochemical water splitting is considered as a novel and promising strategy for hydrogen production. It can effectively convert solar energy into hydrogen storage. In this study, we utilized ß-FeOOH nanoparticles/carbon quantum dots to co-modified WO3 nanoplates and combined with Ar plasma to generate more oxygen vacancy. The detailed mechanisms of CQDs / Ar plasma treated FeOOH @WO3 NPs nanocomposites film is discussed through morphologies, surface chemical elemental composition, crystallinity, band structure, and optical characterizations. The morphologies and microstructures of obtained samples were investigated with TEM and SEM analysis. Uv-vis analysis was used to examine the optical absorption properties after surface modification. The changes of surface chemical states and oxygen vacancy ratio were analyzed by XPS. In addition, the degree of band bending of the interface between nanocomposites and electrolyte after Ar plasma treatment was investigated by UPS and UV-vis analysis. Through systematic analysis, we have a deeper understanding of the mechanism of the CQDs / Ar plasma treated FeOOH @WO3 NPs nanocomposites. Band structure is carried out to demonstrate the synergistic effect between ß-FeOOH and CQD, which is also believed to facilitate the transport of carriers between different materials. After co-modification and Ar plasma treatment, CQDs / Ar plasma treated FeOOH @WO3 NPs exhibited excellent performance for PEC water splitting. The photocurrent density can be significantly increased to 2.18 mA /cm2 at 1.23 V vs. RHE ,which is about 3.5 times higher than that of bare WO3 nanoplates. Furthermore, CQDs / Ar plasma treated FeOOH @WO3 NPs show the highest Electric double layer capacitance of 751 μF∙cm-2 and onset potential also shift cathodically by 257 mV. In the future, we will combine hydrogen storage technology to develop complete energy supply devices and continuous improve the efficiency of PEC system.

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