Carbon quantum dots (CQDs) have demonstrated tremendous potential in enhancing the photocatalytic performance of TiO₂; however, the fabrication of CQDs/TiO₂ composite photocatalysts typically involves harsh reagents/conditions, cumbersome purification procedures and external energy supplies. In this work, we present a facile and energy-efficient impregnation method for the preparation of effective CQDs/TiO₂ composite photocatalysts at room temperature employing coal tar pitch (CTP) as “natural CQDs”. The characterization results indicate that TiO₂ and CQDs can be successfully coupled together by forming Ti‒O‒C bonds. The fabricated CQDs/TiO₂ composites show remarkably improved photodegradation performances of rhodamine B (RhB) under visible-light irradiation, which are far higher than pure TiO₂. At the optimum CQDs content (6 wt%), the degradation rate constant is 43.7-fold higher than that of pure TiO₂. The marked ameliorated photocatalytic performance is attributed to the fact that the successful coupling between TiO₂ and CQDs can ameliorate the absorption ability of visible light, accelerate the separation/transfer of charge carriers and restrain the recombination of photogenerated electron–hole (e⁻–h⁺) pairs. This research provides a facile method for large-scale preparation of CQDs modified semiconductor photocatalysts that can potentially be used in environmental and energy applications.

碳量子点（CQD）在增强TiO ₂的光催化性能方面显示出巨大的潜力。然而，CQDs / TiO ₂复合光催化剂的制备通常涉及苛刻的试剂/条件，繁琐的纯化程序和外部能量供应。在这项工作中，我们提出了一种简便而节能的浸渍方法，以煤焦油沥青（CTP）作为“天然CQD”在室温下制备有效的CQDs / TiO ₂复合光催化剂。表征结果表明，通过形成Ti‒O‒C键可以成功地将TiO ₂和CQD偶联在一起。人造CQDs / TiO ₂复合材料在可见光照射下，若丹明B（RhB）的光降解性能显着提高，远高于纯TiO ₂。在最佳CQDs含量（6 wt％）下，降解速率常数比纯TiO ₂高43.7倍。明显改善的光催化性能归因于以下事实：TiO ₂和CQD之间的成功偶联可以改善可见光的吸收能力，加速电荷载流子的分离/转移，并抑制光生电子-空穴的复合（e ^-- h ⁺）对。这项研究为大规模制备CQDs改性的半导体光催化剂提供了一种简便的方法，该方法可潜在地用于环境和能源应用。