Higher water dissociation (Volmer step) energy barrier leads to the sluggish alkaline hydrogen evolution reaction (HER) rate. Since hydrophilic TiO2 can reduce water dissociation barrier while the widely studied Ru has nearly zero hydrogen adsorption Gibbs free energy, the combination of TiO2 and Ru/C might collectively enhance Volmer and Heyrovsky/Tafel step and finally promote HER performance. Herein, Ru/C−TiO2 with average size of 3.6 nm for Ru was synthesized by a two‐step process. It presented superior alkaline HER activity with η10 of 44 mV, better than that of Ru/C (107 mV), Pt/C (84 mV) and C−TiO2 with negligible activity. The prominent HER performance was due to synergistic effect between TiO2 and Ru, which greatly expedited water dissociation for intermediate hydrogen production and the following electrochemical hydrogen desorption for producing H2. This work combines specific active sites for different elementary steps and then boosts alkaline HER performance, which provide a guide for designing efficient and stable HER electrocatalyst.
Magnetic BiOBr/SrFe12O19 nanosheets were successfully synthesized using the hydrothermal method. The as-prepared samples were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), transmission electron microscope (TEM), and UV-visible diffused reflectance spectra (UV-DRS), and the magnetic properties were tested using a vibration sample magnetometer (VSM). The as-produced composite with an irregular flaky-shaped aggregate possesses a good anti-demagnetization ability (Hc = 861.04 G) and a high photocatalytic efficiency. Under visible light (λ > 420 nm) and UV light-emitting diode (LED) irradiation, the photodegradation rates of Rhodamine B (RhB) using BiOBr/SrFe12O19 (5 wt %) (BOB/SFO-5) after 30 min of reaction were 97% and 98%, respectively, which were higher than that using BiOBr (87%). The degradation rate of RhB using the recovered BiOBr/5 wt % SrFe12O19 (marked as BOB/SFO-5) was still more than 85% in the fifth cycle, indicating the high stability of the composite catalyst. Meanwhile, after five cycles, the magnetic properties were still as stable as before. The radical-capture experiments proved that superoxide radicals and holes were main active species in the photocatalytic degradation of RhB.
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