A critical review of hydrochar based photocatalysts by hydrothermal carbonization: synthesis, mechanisms, and applications

• Published in: Biochar (Online) Vol. 6; no. 1; pp. 1 - 34
• Main Authors: Chen, Zeliang, Guo, Yanchuan, Luo, Lei, Liu, Zhengang, Miao, Wei, Xia, Yu
• Format: Journal Article
• Language: English
• Published: Singapore Springer Nature Singapore 16.08.2024; Springer
• Subjects: Agriculture; Biomass; Carbon dots; Carbon-based composite; Ceramics; Composites; Earth and Environmental Science; Environment; Environmental Engineering/Biotechnology; Fossil Fuels (incl. Carbon Capture); Glass; Hydrochars; Hydrothermal carbonization; Natural Materials; Photocatalysis; Renewable and Green Energy; Review; Soil Science & Conservation; Biomass; Carbon dots; Carbon-based composite; Hydrothermal carbonization; Hydrochars; Photocatalysis
• ISSN: 2524-7867
• DOI: 10.1007/s42773-024-00364-9

Hydrothermal carbonization (HTC) stands out as an eco-friendly, cost-effective method for generating renewable carbon-based materials from biomass. The HTC process yields products such as hydrochars and carbon dots (CDs), possessed of notable photocatalytic capabilities due to their unique physicochemical features. Additionally, pairing traditional photocatalysts with hydrochar derivatives elevates their performance, rendering them more effective. Recent times have witnessed a surge in interest in these hydrochar based photocatalysts (HC-photocatalysts). Their appeal stems from multiple attributes: impeccable performance, adaptability to visible light, and adjustable physicochemical properties. This review delves deep into the evolving landscape of these HC-photocatalysts, segmenting them into three distinct categories: hydrochars, hydrochar-based CDs (HC-CDs), and hydrochar-based composites (HC-composites). For each category, we dissect their synthesis routes, unravel the photocatalytic mechanisms, and explore various enhancement strategies. We further traverse their versatile applications, spanning environmental treatment, disinfection, energy conversion, and organic synthesis. In the end, we spotlight the prevailing challenges and uncharted territories in the domain of HC-photocatalysts. In essence, this review serves as a guide, furnishing a theoretical foundation and steering directions for future explorations and tangible implementations of HC-photocatalysts. Graphical Abstract Highlights Biomass can be converted into highly efficient photocatalysts by HTC. Photocatalytic mechanisms and modifications of hydrochars and HC-CDs are discussed. The roles of carbons in HC-composite photocatalysts are reviewed. HC-photocatalysts have shown various environmental, energy and other applications. Prospects and guidelines for theoretical and application research are listed.