Carbon-Based Photoabsorbers for Sustainable Energy Applications

The continuous air and water pollution arising from the accelerated consumption of fossil fuels and organic pollutants, respectively, emphasize the need for society to move towards renewable “green” resources, and environmentally sustainable processes. Photocatalysis is a promising approach for mitigating simultaneously both the energy and environmental concerns.¹However, the development of economically and environmentally sustainable photocatalytic processes creates the pressing need for new materials of low cost and toxicity, such as photoabsorbers and catalysts, which maintain substantial performances.<br/><br/>Carbon dots (CDs) and carbon nitride (CN_x) can efficiently serve as photoabsorbers for this purpose since they fulfil these requirements.^2-6 In particular, they are hydrophilic materials of low toxicity which are chemically and photochemically robust, can be synthesized at low cost, and show optimum photocatalytic properties upon pre-designed synthesis. In this work, we describe the synthesis of CN_xand CDs from low-cost organics and/or Earth abundant waste (circular economy), the structure of which bestows the derived photoabsorbers with distinctive photocatalytic performances. These light harvesters, when combined with noble-metal free catalysts in aqueous photocatalytic systems, not only facilitate “green”, solar-driven fuel synthesis but also waste/water pollutant utilization. The use of waste and aqueous pollutants, eliminates the need for additional sacrificial reagents traditionally used in great excess, which add to the overall cost of the process, and result in toxic by-products.⁷ We anticipate that this approach could be a breakthrough in the development of scalable, economically, and environmentally sustainable systems, which can efficiently serve energy and environmental applications.<br/><br/><b>References</b><br/>1. Kamat, P. V.; Bisquert, J., <i>J. Phys. Chem. C </i><b>2013,</b> <i>117</i>, 14873-14875.<br/>2. Achilleos, D. S.; Kasap, H.; Reisner, E., <i>Green Chem. </i><b>2020,</b> <i>22</i>, 2831-2839.<br/>3. Achilleos, D. S.; Yang, W.; Kasap, H.; Savateev, A.; Markushyna, Y.; Durrant, J. R.; Reisner, E., <i>Angew. Chem. Int. Ed. </i><b>2020,</b> <i>59</i>, 18184-18188.<br/>4. Kasap, H.; Achilleos, D. S.; Huang, A.; Reisner, E., <i>J. Am. Chem. Soc. </i><b>2018,</b> <i>140</i>, 11604-11607.<br/>5. Kasap, H.; Godin, R.; Jeay-Bizot, C.; Achilleos, D. S.; Fang, X.; Durrant, J. R.; Reisner, E., <i>ACS Catalysis </i><b>2018,</b> <i>8</i>, 6914-6926.<br/>6. Ren, J.; Achilleos, D. S.; Golnak, R.; Yuzawa, H.; Xiao, J.; Nagasaka, M.; Reisner, E.; Petit, T., <i>J. Phys. Chem. </i><i>Lett. </i><b>2019,</b> <i>10</i>, 3843-3848.<br/>7. Pellegrin, Y.; Odobel, F., <i>C. R. Chim. </i><b>2017,</b> <i>20</i>, 283-295.