Beiler Anna M, McCarthy Brian D, Johnson Ben A, Ott Sascha
Department of Chemistry, Ångström Laboratory, Uppsala University, Box 523, 75120, Uppsala, Sweden.
Nat Commun. 2020 Nov 16;11(1):5819. doi: 10.1038/s41467-020-19483-5.
Surface modification of semiconductors can improve photoelectrochemical performance by promoting efficient interfacial charge transfer. We show that metal-organic frameworks (MOFs) are viable surface coatings for enhancing cathodic photovoltages. Under 1-sun illumination, no photovoltage is observed for p-type Si(111) functionalized with a naphthalene diimide derivative until the monolayer is expanded in three dimensions in a MOF. The surface-grown MOF thin film at Si promotes reduction of the molecular linkers at formal potentials >300 mV positive of their thermodynamic potentials. The photocurrent is governed by charge diffusion through the film, and the MOF film is sufficiently conductive to power reductive transformations. When grown on GaP(100), the reductions of the MOF linkers are shifted anodically by >700 mV compared to those of the same MOF on conductive substrates. This photovoltage, among the highest reported for GaP in photoelectrochemical applications, illustrates the power of MOF films to enhance photocathodic operation.
半导体的表面改性可通过促进高效的界面电荷转移来改善光电化学性能。我们表明，金属有机框架（MOF）是用于增强阴极光电压的可行表面涂层。在1个太阳光照下，用萘二亚胺衍生物功能化的p型Si(111)在MOF中三维扩展单层之前未观察到光电压。在Si上表面生长的MOF薄膜促进了分子连接体在比其热力学电位正>300 mV的形式电位下的还原。光电流由通过薄膜的电荷扩散控制，并且MOF薄膜具有足够的导电性来驱动还原转化。当生长在GaP(100)上时，与在导电基底上的相同MOF相比，MOF连接体的还原向阳极移动了>700 mV。这种光电压是光电化学应用中报道的GaP的最高光电压之一，说明了MOF薄膜增强光电阴极操作的能力。
