Abstract The synthesis of metal-free graphene-based photocatalysts has received great attention recently due to their expected contributions to the development of solar-based hydrogen generation via water-splitting in a low cost and ecological manner. In this work, a new method for the generation of nitrogen-doped graphene-based powder employing an alternative solution to commonly used toxic and hazardous organic solvents is presented. The procedure involves ultraviolet pulsed laser irradiation of graphene oxide (GO) flakes dispersed in 1-butyl-3-methylimidazolium [bmim]-based ionic liquids using both chloride and acetate anions. The structural and compositional analysis using transmission electron microscopy, X-ray photoelectron and infrared spectroscopy indicate that the irradiated GO becomes partially reduced and doped with graphitic, pyrrolic and pyridinic nitrogen species. Interestingly, the relative content of the nitrogen functionalities is controlled by the anion in the ionic liquid and its concentration, with the obtained graphene-based powders showing higher photocatalytic activity than GO. Furthermore, a remarkable synergistic effect is observed for GO-[bmim]-acetate powder (acting as co-catalyst) in combination with anatase TiO2 nanoparticles. The presented method opens new research avenues for the cost-effective mass production of graphene-based photocatalysts for water splitting applications.

中文翻译：

---

通过激光诱导掺杂离子液体合成用于分解水的石墨烯基光催化剂

摘要 无金属石墨烯基光催化剂的合成近年来受到了极大的关注，因为它们有望以低成本和生态的方式通过水分解太阳能制氢的发展。在这项工作中，提出了一种使用常用有毒和危险有机溶剂的替代解决方案来生成氮掺杂石墨烯基粉末的新方法。该过程涉及使用氯离子和乙酸根阴离子对分散在 1-丁基-3-甲基咪唑鎓 [bmim] 基离子液体中的氧化石墨烯 (GO) 薄片进行紫外线脉冲激光照射。使用透射电子显微镜、X 射线光电子和红外光谱进行的结构和成分分析表明，受照射的 GO 部分还原并掺杂有石墨，吡咯和吡啶氮种类。有趣的是，氮官能团的相对含量受离子液体中的阴离子及其浓度控制，获得的石墨烯基粉末显示出比 GO 更高的光催化活性。此外，观察到 GO-[bmim]-醋酸盐粉末（作为助催化剂）与锐钛矿 TiO2 纳米颗粒的组合具有显着的协同效应。所提出的方法为具有成本效益的大规模生产用于水分解应用的石墨烯基光催化剂开辟了新的研究途径。对于 GO-[bmim]-乙酸盐粉末（作为助催化剂）与锐钛矿 TiO2 纳米颗粒的组合观察到显着的协同效应。所提出的方法为具有成本效益的大规模生产用于水分解应用的石墨烯基光催化剂开辟了新的研究途径。对于 GO-[bmim]-乙酸盐粉末（作为助催化剂）与锐钛矿 TiO2 纳米颗粒的组合观察到显着的协同效应。所提出的方法为具有成本效益的大规模生产用于水分解应用的石墨烯基光催化剂开辟了新的研究途径。