Developing efficient water oxidation catalysts made of earthabundant elements is a demanding challenge that should be met to fulfill the promise of water splitting for clean energy. Herein we report an annealing approach to synthesize binder-free, self-supported heterogeneous copper oxide (CuO) on conductive electrodes for oxygen evolution reaction (OER), producing electrodes with excellent electrocatalytic properties such as high efficiency, low overpotential, and good stability. The catalysts were grown in situ on fluorine-doped tin oxide (FTO) by electrodeposition from a simple Cu(II) salt solution, followed by annealing at a high temperature. Under optimal conditions, the CuO-based OER catalyst shows an onset potential of <0.58 V (vs Ag/AgCl) in 1.0 M KOH at pH 13.6. From the Tafel plot, the required overpotentials for current densities of 0.1 and 1.0 mA/cm 2 are only 360 and 430 mV, respectively. The structure and the presence of a CuO motif in the catalyst have been identified by high-energy X-ray diffraction (HE-XRD), Cu K-edge X-ray absorption (XAS) spectra including X-ray absorption near-edge structure (XANES), and extended X-ray absorption fine structure (EXAFS). To the best of our knowledge, this represents the best catalytic activity for CuO-based OER catalysts to date.
This study presents synthesis and characterizations of two novel curved nanographenes that strongly bind with fullerene C 60 to form photoconductive heterojunctions.F ilms of the self-assembled curved nanographene/fullerene complexes,w hichs erved as the photoconductive layer,g enerated as ignificant photocurrent under light irradiation. Gram-scale quantities of these curved nanographenes (TCR and HCR) as the "crown" sidewalls can be incorporated into ac arbon nanoring to form molecular crowns,a nd the molecular structure of C 60 @TCR is determined by single-crystal X-ray diffraction. The UV/Vis absorption and emission spectra, and theoretical studies revealed their unique structural features and photophysical properties.T ime-resolved spectroscopic results clearly suggest fast photoinduced electron transfer process in the supramolecular heterojunctions. Figure 5. a) Differentiala bsorption spectra obtained upon femtosecond pump-probe experiments (370 nm) of C 60 @HCR complex in chlorobenzene with time delays of 2, 25, and 370 ps at room temperature. b) Time-absorption profile and corresponding fitting line of the absorption of the HCR radical cation at 509 nm.
The development of efficient water-oxidation electrocatalysts based on inexpensive and earth-abundant materials is significant to enable water splitting as a future renewable energy source. Herein, the synthesis of novel FeNiP solid-solution nanoplate (FeNiP-NP) arrays and their use as an active catalyst for high-performance water-oxidation catalysis are reported. The as-prepared FeNiP-NP catalyst on a 3D nickel foam substrate exhibits excellent electrochemical performance with a very low overpotential of only 180 mV to reach a current density of 10 mA cm and an onset overpotential of 120 mV in 1.0 m KOH for the oxygen evolution reaction (OER). The slope of the Tafel plot is as low as 76.0 mV dec . Furthermore, the long-term electrochemical stability of the FeNiP-NP electrode is investigated by cyclic voltammetry (CV) at 1.10-1.55 V versus reversible hydrogen electrode (RHE), demonstrating very stable performance with negligible loss in activity after 1000 CV cycles. This present FeNiP-NP solid solution is thought to represent the best OER catalytic activity among the non-noble metal catalysts reported so far.
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