碳点增强的Ru纳米颗粒复合材料用于碱性条件下高效电解水析氢

Carbon Dots Enhance Ruthenium Nanoparticles for Efficient Hydrogen Production in Alkaline

氢能源被认为是二十一世纪的新型能源,其有望解决由传统化石燃料的过度使用而带来的环境污染和全球变暖等问题。电解水析氢(HER)因其绿色环保的特点引起了巨大的关注。同时,为进一步提升电催化剂的催化性能和降低其制作成本,碳基金属杂化材料被开发出来并表现出高效的催化活性。其中,碳点(CDs)因其合成方便、生物相容性好、色彩丰富、化学稳定性好和优异的电子传导性能,在传感、生物成像及源转换方面有良好的应用潜力。碳点通常作为载体被广泛应用在碳基金属杂化材料电催化剂的构筑上,目前,普遍认为碳点具有优异的限域作用,能够有效地抑制金属纳米颗粒的生长和团聚,从而制备出分布均匀,尺寸可控的碳基金属杂化材料,然而,从小分子原料到碳点的形成过程却鲜有报道。在本研究中,我们以碳点和合成碳点的小分子原料为前驱体,分别制备了氮掺杂的高结晶性碳点负载的钌纳米颗粒杂化材料(Ru@CDs)和小分子负载的钌纳米颗粒杂化材料(Ru@Molecule),探究了小分子在形成碳点的过程中和Ru之间的相互作用以及对电解水析氢反应(HER)性能的影响。同时,我们制备了金属有机骨架(MOF)、碳纳米管(CNTs)、石墨烯(GO)等不同载体,构建了不同碳基载体负载的Ru纳米颗粒(Ru@M)。其中,以碳点作为载体制备的Ru@CDs杂化材料,Ru纳米颗粒在尺寸和分散性上都是可控的,活性位点有效暴露,表现出优异的HER活性和良好的稳定性,在电流密度为10 mA·cm^(-2)时的过电位仅为22 mV。研究表明,从小分子到碳点的形成需经过一个中间态,而中间态无限域作用,随着煅烧温度的升高,小分子逐渐向碳点转变。碳点与金属离子之间的配位作用形成这种独特的空间限域作用是形成单分散Ru纳米颗粒的关键。因此,碳点是优异的HER催化剂载体。该工作不仅揭露了碳点的独特的空间限域能力对所负载金属的作用及其对电催化活性的影响,同时也为将来碳点基金属电催化剂的开发提供了参考。

In the 21st century,hydrogen energy is a novel energy source.Its use is expected to mitigate the problems of environmental pollution and global warming caused by the excessive use of conventional fossil fuels.The hydrogen evolution reaction(HER)for water splitting has attracted considerable attention because of its environmental friendliness.To improve electrocatalyst performance and reduce operation cost,carbon-based metal hybrid materials exhibiting high efficiency and catalytic activity have been developed.Among them,carbon dots(CDs)have garnered significant research attention and have been widely applied in biosensing,bioimaging,and energy conversion/storage because of their facile synthesis,biocompatibility,tunable photoluminescence,excellent stability,and good electronic properties.CDs are widely used as carriers in the construction of electrocatalysts prepared from carbon-based metal hybrid materials.At present,it is believed that CDs exhibit excellent confinement effects,which can effectively inhibit the growth and agglomeration of metal nanoparticles,thereby preparing well-distributed carbon-based metal hybrid materials with a uniform and controllable size.However,the formation process of the small-molecule raw materials of CDs has not been elucidated.In this study,CDs and small-molecule raw materials from synthetic CDs were used as precursors to prepare nitrogen-doped CD-supported ruthenium nanoparticle(Ru@CDs)and small-molecule-supported ruthenium nanoparticle(Ru@Molecule)hybrid materials,respectively.The interaction between the small molecules and Ru in the process of CD formation and the effect on HER performance were explored.Moreover,we prepared different carriers such as metal organic frameworks(MOF),carbon nanotubes(CNTs),and graphene(GO)-supported ruthenium nanoparticle hybrid materials.Among them,Ru@CDs exhibited controllable size and excellent dispersibility and exhibited outstanding HER activity and good stability.Ru@CDs were found to require a low overpotential of 22 mV to reach a current density of 10 mA·cm^(-2).Moreover,we observed the presence of an intermediate state between the molecules and CDs and demonstrated that the intermediate state exhibits no confinement effect.Furthermore,we found that with increasing calcination temperature,the intermediate state gradually changes to CDs.The unique spatial confinement between CDs and metal ions is key to the formation of monodisperse Ru nanoparticles.Our results confirmed that Ru@CDs serve as excellent HER catalyst supports.This work not only reveals the effect of the unique spatial confinement of CDs on the supported metals and their promoting effect on electrocatalytic activity but also provides guides the future development of CD-based metal hybrid electrocatalysts.