Structure Engineering of Carbon-based Materials for Efficient Photocatalysis

• 資料種別: 博士論文
• タイトル: Structure Engineering of Carbon-based Materials for Efficient Photocatalysis
• 著者・編者: 李, 云祥
• 著者標目: 李, 云祥
• 出版事項: Hokkaido University
• 出版年月日等: 2020-03-25
• 出版年（W3CDTF）: 2020-03-25
• 並列タイトル等: 高効率光触媒の構築に向けた炭素系材料の構造制御に関する研究
• 寄与者: 加藤, 昌子; 武田, 定; 葉, 金花; 白幡, 直人; 藤田, 進一郎
• 授与機関名: 北海道大学
• 授与年月日: 2020-03-25
• 授与年月日（W3CDTF）: 2020-03-25
• 報告番号: 甲第14013号
• 学位: 博士(理学)
• 博論授与番号: 甲第14013号
• 本文の言語コード: eng
• NDC: 400
• 対象利用者: 一般
• 一般注記: Metal free carbon-based materials, featuring low cost, editable structure and unique physicochemical property, are promising candidates for photocatalytic systems. Among them, polymeric carbon nitride (CN) has attracted extensive attention as photocatalyst in recent years due to its low cost, ease of synthesis, and appropriate band structure. However, efficient solar-to-energy conversion over CN still encounters great challenges because of its inherent drawbacks, such as the fast recombination of photocarriers, poor electronic conductivity. Furthermore, the lack of robust active sites on carbon co-catalysts and interfacial contamination with adventitious carbon severely limit the overall photocatalytic efficiency of carbon-based photocatalytic systems. In this work, the object is to design and develop carbon-based materials via modulating the intrinsic properties of photocatalyst CN, creating novel carbon-based co-catalyst and removing the relevant interfacial adventitious carbon for efficient photochemical processes and thus to further understandings of carbon-based materials as well as the corresponding mechanism of photocatalysis. In chapter 1, an overview of photocatalysis was introduced first. Then, a review of photocatalytic system, including the photocatalysts, co-catalysts, interfaces and relevant modulation strategies, was given. In the end, the recent development of carbon-based photocatalytic system was summarized. In chapter 2, to improve the poor electronic conductivity of CN and thus to promote the charge carrier transfer and separation behavior, a conceptual and facile strategy was developed to construct carbon chains incorporated CN. Various kinds of carbon chains can connect the in-plane defects of CN via strong covalent C-N bonds. Those embedded atomic carbon chains could efficiently mediate the electron transfer in the basal plane of CN. As a result, the optimal carbon chains-planted CN delivers a remarkably enhanced photocatalytic performance, achieving a 13.2 and 29.2-fold improvement in H2 evolution and CO2 reduction, respectively. This study provides an in-depth insight into the modulation of in-plane electrical conductivity at molecular scale over CN and offers new opportunities for reinforcing the reaction kinetics of organic-based photocatalysts. In chapter 3, a facile, green, and reversible exfoliation-reassembly strategy was developed to switch the features of polymeric CN for different photoredox reactions. The OH groups are implanted between the layers of CN in advance, then the introduced smallsized protons enter into the layer spacing and neutralize the OH to produce H2O. The giant expansion effect of in situ-generated H2O molecules confined to the interlayer results in the mass production of ultrathin polymeric CN nanosheets, giving a high yield, i.e., up to 48%, of ultrathin nanosheets in a mild solution (pH ~1.3). Interestingly, the exfoliation-reassembly process, as well as the properties of CN are largely reversible via alternating the interlayer groups. Moreover, the exfoliated and reassembled CN achieve a superior photocatalytic activity for iso-propanol (IPA) degradation (acetone: 345 µmol/h; CO2: 23 µmol/h) and H2 evolution (1370 µmol/h), resulting in a high apparent quantum yield (AQY) of 27% and 46%, respectively, at ~420 nm. This new proof-ofconcept strategy will open up further opportunities for more effective delamination of extensive layered 2D materials towards advanced applications. In chapter 4, a robust single cobalt co-catalyst Co-NC (with isolated Co-N4 moieties on N-rich carbon sheets) was fabricated and anchored on photoharverster CdS. Subsequently, the interfacial adventitious carbon between CdS and Co-NC was targetedly removed by a facile annealing process, resulting in a cleared interface with small resistance. It’s found that surface-trapped electrons can readily migrate to the firmly attached Co-NC across the cleared interface between CdS and Co-NC. The smallresistance interfacial carrier path and the robust single-cobalt sites work in a cooperative way and hence achieve a superior visible-light-driven H2 generation activity with a rate of 4.34 mmol/h, an apparent quantum yield (AQY) of 63.9 % at 400 nm and a ultrahigh turnover frequency (TOF) of up to 16714.7 h-1. This finding will motivate future work in creating clean interfaces and unique single active sites for high-performance photocatalysis. In chapter 5, an overall summary of this dissertation work was presented. This thesis carried out a systematic study on the construction of efficient carbon-based materials for visible-light-driven photocatalytic reactions, including H2 evolution, CO2 reduction, and isopropanol (IPA) degradation. This thesis reveals that the structure engineering carbonbased materials and relevant interfaces are of significance to improve photocatalytic activity. Furthermore, the findings in this study also deepen the understanding of carbonbased photocatalytic systems, shed light on the mechanism of photocatalysis, and importantly, highlight some universal design strategies for efficient photochemistry processes.; (主査) 教授 加藤 昌子, 特任教授 武田 定, 客員教授 葉 金花, 客員教授 白幡 直人, 講師 藤田 進一郎; 総合化学院（総合化学専攻）
• DOI: 10.14943/doctoral.k14013; https://doi.org/10.14943/doctoral.k14013
• 国立国会図書館永続的識別子: info:ndljp/pid/11660409; https://dl.ndl.go.jp/pid/11660409
• コレクション（共通）: 障害者向け資料
• コレクション（障害者向け資料：レベル1）: テキストデータ
• コレクション（個別）: 国立国会図書館デジタルコレクション > デジタル化資料 > 博士論文; https://dl.ndl.go.jp/collections/A00014
• 収集根拠: 博士論文（自動収集）
• 受理日（W3CDTF）: 2021-04-07T03:01:57+09:00
• 作成日（W3CDTF）: 2020
• 記録形式（IMT）: PDF
• オンライン閲覧公開範囲: 国立国会図書館内限定公開
• デジタル化資料送信: 図書館・個人送信対象外
• 遠隔複写可否（NDL）: 可
• 掲載誌（URI）: http://dx.doi.org/10.14943/doctoral.k14013; http://hdl.handle.net/2115/80638
• 参照（URI）: http://hdl.handle.net/2115/78136
• 連携機関・データベース: 国立国会図書館 : 国立国会図書館デジタルコレクション; https://dl.ndl.go.jp

• 要約等: Metal free carbon-based materials, featuring low cost, editable structure and unique physicochemical property, are promising candidates for photocatal...