RESUMEN
The development of highly efficient electrocatalysts for direct seawater splitting with bifunctionality for inhibiting anodic oxidation reconstruction and selective oxygen evolution reactions is a major challenge. Herein, we report a direct seawater oxidation electrocatalyst that achieves long-term stability for more than 1000 h at 600 mA/cm2@η600 and high selectivity (Faraday efficiency of 100%). This catalyst revolves an amorphous molybdenum oxide layer constructed on the beaded-like cobalt oxide interface by atomic layer deposition technology. As demonstrated, a new restricted dynamic surface self-reconstruction mechanism is induced by the formation a stable reconstructed Co-Mo double hydroxide phase interface layer. The device assembled into a two-electrode flow cell for direct overall seawater electrolysis maintained at 1 A/cm2@1.93 V for 500 h with Faraday efficiency higher than 95%. Hydrogen generation rate reaches 419.4 mL/cm2/h, and the power consumption (4.62 KWh/m3 H2) is lower than that of pure water (5.0 KWh/m3 H2) at industrial current density.
RESUMEN
Bimetallic layered double hydroxide is considered an ideal electrocatalytic material. However, due to the poor electrical conductivity of the bimetallic layered structure, obtaining highly active and stable catalysts through facile regulation strategies remains a great challenge. Herein, we use a simple corrosion strategy and nitrogen plasma technology to convert cobalt-based metal-organic frameworks into nitrogen-doped CoMn bimetallic layered double hydroxides (CoMn-LDH). Under the condition of regulating the local coordination environment of the catalytic active site and the presence of rich oxygen vacancy defects, N@CoMn-LDH/CC generates a low overpotential of 219 mV at 10 mA cm-2, which exceeds that of the commercial RuO2 catalyst. Density functional theory calculation shows that nitrogen doping improves the adsorption energy of the Mn site for oxygen evolution intermediates and reduces the reaction energy barrier of the Co site. Meanwhile, experiments and theoretical calculations verify that the mechanism of nitrogen doping regulating the oxygen evolution reaction (OER) follows the lattice oxygen oxidation mechanism, avoiding the collapse of the structure caused by catalyst reconstruction, thus improving the stability of oxygen evolution. This work provides a new simple strategy for the preparation of catalysts for a superior electrocatalytic oxygen evolution reaction.
RESUMEN
The precatalyst undergoes surface reconstruction during the oxygen evolution reaction (OER) process, and the reconstituted material is the one that really plays a catalytic role. However, the degree of surface reconstruction seriously affects the catalytic performance. For this reason, it is important to establish the link between the degree of reconstruction and catalytic activity based on a deep understanding of the OER mechanism for the rational design of high-performance OER electrocatalysts. Here, the reaction mechanism of OER is briefly introduced, the competition between adsorbate evolution mechanism (AEM) mechanism and lattice oxygen-mediated mechanism (LOM) mechanism is discussed, and several activity descriptors of OER reaction are summarized. The strategies to realize OER controllable surface reconstruction are emphatically introduced, including ion leaching, element doping, regulating catalyst size, heterogeneous structure engineering, and self-reconstruction. A mechanistic perspective is emphasized to understand the relationship between dynamic surface reconstruction and electronic structure. Controlled reconfiguration of OER surface can break the limitation of proportional relationship brought by traditional AEM mechanism, also can realize the switching between AEM mechanism and LOM mechanism, thus realizing ultra-low overpotential. This review will provide some reference for surface controllable reconstruction of OER transition metal-based catalysts and reasonable development of ideal catalytic performance.