Photocatalytic CO2 reduction coupled with water oxidation provides a fascinating approach to mitigating the issues of global warming and energy shortage. Herein, a direct Z-scheme heterojunction of Co1-C3N4@α-Fe2O3 comprising g-C3N4-supported...
The evident demand for hydrogen as the ultimate energy fuel for posterity calls for the development of low-cost, efficient and stable electrocatalysts for water splitting. Herein, we report the synthesis of Co/CoO x supported on coal-derived N-doped carbon via a simple microwave-assisted method and demonstrate its application as an efficient catalyst for the oxygen evolution reaction (OER). With the optimal amount of cobalt introduced into the N-doped coal-derived, the developed catalyst achieved overpotentials of 0.370 and 0.429 V during water oxidation at current densities of 1 mA cm −2 and 10 mA cm −2 , respectively. There was no noticeable loss in the activity of the catalyst during continuous galvanostatic polarization at a current density of 10 mA cm −2 for a test period of 66 h. The synergistic interaction of the Co/CoO x moieties with the pyridinic and pyrollic nitrogen functional groups in the N-doped carbon, as well with the other heteroatoms species in the pristine coal favored enhancement of the OER electrocatalytic performance.
Sunlight-driven activation of molecular oxygen (O 2 ) for organic oxidation reactions offers an appealing strategy to cut down the reliance on fossil fuels in chemical industry, yet it remains a great challenge to simultaneously tailor the charge kinetics and promote reactant chemisorption on semiconductor catalysts for enhanced photocatalytic performance. Herein, we report iron sites immobilized on defective BiOBr nanosheets as an efficient and selective photocatalyst for activation of O 2 to singlet oxygen ( 1 O 2 ). These Fe 3+ species anchored by oxygen vacancies can not only facilitate the separation and migration of photogenerated charge carrier, but also serve as active sites for effective adsorption of O 2 . Moreover, low-temperature phosphorescence spectra combined with X-ray photoelectron spectroscopy (XPS) and electronic paramagnetic resonance (EPR) spectra under illumination reveal that the Fe species can boost the quantum yield of excited triplet state and accelerate the energy transfer from excited triplet state to adsorbed O 2 via a chemical loop of Fe 3+ /Fe 2+ , thereby achieving highly efficient and selective generation of 1 O 2 . As a result, the versatile iron sites on defective BiOBr nanosheets contributes to near-unity conversion rate and selectivity in both aerobic oxidative coupling of amines to imines and sulfoxidation of organic sulfides. This work highlights the significant role of metal sites anchored on semiconductors in regulating the charge/energy transfer during the heterogeneous photocatalytic process, and provides a new angle for designing high-performance photocatalysts.
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