摘要
CeO 2 -Co 3 O 4 electrocatalyst is constructed via Hard-Soft-Acid-Base theory. • CeO 2 as hard acid prefers to OH − , while Co sites bind soft S-containing bases. • The catalyst exhibits a current density of 100 mA cm −2 at a potential of 0.31 V. • The HER||SOR system indicates the application potential of CeO 2 -Co 3 O 4 . Sulfide oxidation reaction (SOR) is not only a suitable substitution technology for anodic reaction in overall water splitting but also an emerging technology to replace conventional sulfide abatement strategies. However, the restricted adsorption/desorption process of key intermediates still limit the development of SOR. In this work, basic hard-soft-acid-base (HSAB) theory is employed to regulate the acid hardness of Co 3 O 4 to enhance the dynamic behavior of the key intermediates. Theoretical prediction results indicate the CeO 2 is the suitable hard acid carrier and then the CeO 2 -Co 3 O 4 is prepared via a one-step hydrothermal method followed by calcination. The optimized CeO 2 -Co 3 O 4 catalyst exhibits a current density of 100 mA cm −2 at a low potential of 0.31 V (vs. RHE) and outstanding long-term durability. A current density of 400 mA cm −2 is achieved at 1.13 V (70 °C) in two-electrode flow electrolysis of 0.5 M Na 2 S (HER||SOR). Detailed experimental and theoretical studies indicate the incorporation of CeO 2 creates hard Lewis-acidic sites that preferentially interact with OH − , while Co sites retain moderate affinity toward soft sulfur-containing bases such as HS − /polysulfides. This hard–soft acid-site cooperation not only facilitates the progression of the SOR reaction but also effectively inhibits sulfur accumulation at the cobalt active sites. Furthermore, several catalysts are also prepared based on HSAB theory and their enhanced SOR performances indicate the universality of HSAB theory. Download: Download high-res image (163KB) Download: Download full-size image
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