Jian Jing-xin et. al. published a paper on Energy & Environmental Science on April 16, 2016.
Recently, Jian Jing-xin et. al. published a paper on Energy & Environmental Science on April 16, 2016. In this work, we designed two simple water soluble [FeFe]-H2ase mimics Fe2S2-2SO3Na (1) and Fe2S2-SO3Na (2), to construct photocatalytic H2 evolution systems in aqueous solution by using molecular Ru(bpy)3Cl2 (system I) or CdSe QDs (system II) as PS (Fig. 1). Our results reveal that molecular Ru(bpy)3Cl2 systems I showed TONs of 178 for 1 and 114 for 2 and initial TOFs of 0.05 s-1 for 1 and 0.02 s-1 for 2, while CdSe QDs systems II showed more than 100 times larger TONs of 2.65 × 104 for 1 and 1.88 × 104 for 2, and initial TOF of 3.46 s-1 for 1 and 2.11 s-1 for 2. Detailed study on mechanism by electrochemical and time-resolved spectroscopic experiments proved that electron transfer could only be allowed between [FeFe]-H2ase mimics and the reduced state [Ru(bpy)3]+ through reductive-quenching by sacrificial electron donor rather than excited [Ru(bpy)3]2+. On the contrary, electron transfer can occur directly between CdSe QDs and [FeFe]-H2ase mimics through oxidative-quenching with ket of 7.10 × 1011 M-1s-1 for 1 and 3.33 × 1011 M-1s-1 for 2. Further exploration by spectroelectrochemical and transient absorption analysis indicated that the intermediate species [FeIFe0], originated from [FeFe]-H2ase mimics by accepting an electron, could subsequently react with proton to form [FeIFeIIH] species with rate constants calculated to be 1.17 × 107 M-1s-1 for 1 and 8.62 × 106 M-1s-1 for 2. All the results suggest that the native properties of PS and its interaction with [FeFe]-H2ase mimic and sacrificial electron donor and proton source greatly affect the performance of the photocatalytic systems, which is the guidance for the sophisticated design of effective photocatalytic H2 evolution systems.
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