Chemistry Research Unit (CIQUP), Faculty of Sciences of University of Porto, R. Campo Alegre 697, 4169-007 Porto, Portugal.
Chemistry Research Unit (CIQUP), Faculty of Sciences of University of Porto, R. Campo Alegre 697, 4169-007 Porto, Portugal; LACOMEPHI, GreenUPorto, Department of Geosciences, Environmental and Territorial Planning, Faculty of Sciences of University of Porto, R. Campo Alegre 697, 4169-007 Porto, Portugal.
NanoImpact. 2021 Jul;23:100332. doi: 10.1016/j.impact.2021.100332. Epub 2021 Jun 8.
Carbon dots (CDs) are carbon-based nanomaterials with advantageous luminescent properties, making them promising alternatives to other molecular and nanosized fluorophores. However, the development of CDs is impaired by the low synthesis yield of standard fabrication strategies, making high-yield strategies essential. To help future studies to focus on cleaner production strategies, we have employed a Life Cycle Assessment (LCA) to compare and understand the environmental impacts of available routes for the high-yield synthesis of carbon dots. These routes were: (1) production of hydrochar, via hydrothermal treatment of carbon precursors, and its alkaline-peroxide treatment into high-yield carbon dots; (2) thermal treatment of carbon precursors mixed in a eutectic mixture of salts. Results show that the first synthesis route is associated with the lowest environmental impacts. This is attributed to the absence of the mixture of salts in the first synthesis route, which offsets its higher electricity consumption. Sensitivity analysis showed that the most critical parameter in the different synthetic strategies is the identity of the carbon precursor, with electricity being also relevant for the first synthesis route. Nevertheless, the use of some carbon precursors (as citric acid) with higher associated environmental impacts may be justified by their beneficial role in increasing the luminescent performance of carbon dots. Thus, the first synthesis route is indicated to be the most environmental benign and should be used as a basis in future studies aimed to the cleaner and high-yield production of carbon dots.
碳点（CDs）是一种基于碳的纳米材料，具有有利的发光性能，是其他分子和纳米荧光团的有前途的替代品。然而，由于标准制造策略的合成产率低，限制了 CDs 的发展，因此需要高产率的策略。为了帮助未来的研究专注于更清洁的生产策略，我们采用生命周期评估（LCA）来比较和理解高产量合成碳点的现有途径的环境影响。这些途径是：（1）通过水热预处理碳前体生产水热炭，然后用碱性过氧化物处理水热炭以获得高产率的碳点；（2）在盐共晶混合物中热处理碳前体。结果表明，第一种合成路线与最低的环境影响有关。这归因于第一种合成路线中没有盐的混合物，从而抵消了其较高的电力消耗。敏感性分析表明，不同合成策略中最关键的参数是碳前体的身份，而对于第一种合成路线，电力也很重要。然而，使用一些具有较高环境影响的碳前体（如柠檬酸）可能是合理的，因为它们在提高碳点的发光性能方面具有有益的作用。因此，第一种合成路线被认为是最环保的，应作为未来旨在实现碳点清洁和高产的研究的基础。
