| 초록 |
Solar conversion of carbon dioxide and water to value-added chemical fuels remains a challenge. A number of solar-active materials have been reported but still require expensive components and complicated synthetic processes and operate mostly under chemical or electrical bias. In addition, these materials suffer from low selectivity, poor energy efficiency, and instability and fail to drive simultaneous water oxidation. Herein, we report CuFeO2 and CuO mixed p-type materials fabricated via a widely employed electroplating of earth-abundant cupric and ferric ions followed by annealing under atmospheric air. Wired CuO/CuFeO2 photocathode and Pt anode couples produced formate over 1 week at a solar-to-formate energy conversion efficiency of ~1% (selectivity ＞ 90%) without any external bias while O2 was evolved from water under simulated solar light (Air Mass 1.5, 100 mW/cm2). Isotope and nuclear magnetic resonance analyses confirmed the simultaneous production of formate and O2 at the stand-alone couples. An as-synthesized photocatalyst film with a three-dimensional, double-layer configuration further shows the continued production of formate for over 17 days. However, the crystalline structure and elemental state of the used photocatalysts undergo gradual chemical reduction. Such a deformation can be thermally healed by recycling the weekly used samples via oxidative annealing. Thus, a single photocatalyst sample produces formate continuously for 35 days. The photocatalyst components (Cu, Fe, and O) are earth-abundant, and the photocatalyst synthesis is straightforward, facile, environmentally benign, reproducible, and scalable. On achieving higher efficiencies in the future, the practical applicability of these photocatalysts will become enormous. |
