Enhanced borohydride oxidation on Pd-Ni(OH)2/C catalyst via hydroxyl enrichment nearby active sites

Abstract

Direct borohydride fuel cell (DBFC) has been widely investigated due to its practical significance in mobile and portable devices. Pd-based catalysts exhibit superior performance as anode catalysts in DBFCs, but their too strong adsorption of H intermediates (Had) impedes the regeneration of active sites, significantly restricting their stability and final industrial application. In this work, we introduced Ni(OH)2 into Pd/C matrix to enrich OH- for removing Had species. The obtained bimetallic oxides supported on the carbon powder (Pd-Ni(OH)2/C) showed a peak power density of 625 mW cm-2 in DBFC (with air as the cathode oxidant), which is 2.3 times higher than that of the Pd/C, and afforded a remarkable stability of over 120 h at 200 mA cm-2. In-situ spectroscopy studies and theoretical results have revealed that the enriched OH- microenvironment induced by Ni(OH)2 facilitates the oxidative removal of Had on nearby Pd sites, thereby enhancing the regeneration of active sites and substantially boosting the electrocatalytic performance.