Abstract
Electrochemical alcohols oxidation offers a promising approach to produce valuable chemicals and facilitate coupled H2 production. However, the corresponding current density is very low at moderate cell potential that substantially limits the overall productivity. Here we report the electrooxidation of benzyl alcohol coupled with H2 production at high current density (540 mA cm−2 at 1.5 V vs. RHE) over a cooperative catalyst of Au nanoparticles supported on cobalt oxyhydroxide nanosheets (Au/CoOOH). The absolute current can further reach 4.8 A at 2.0 V in a more realistic two-electrode membrane-free flow electrolyzer. Experimental combined with theoretical results indicate that the benzyl alcohol can be enriched at Au/CoOOH interface and oxidized by the electrophilic oxygen species (OH*) generated on CoOOH, leading to higher activity than pure Au. Based on the finding that the catalyst can be reversibly oxidized/reduced at anodic potential/open circuit, we design an intermittent potential (IP) strategy for long-term alcohol electrooxidation that achieves high current density (>250 mA cm−2) over 24 h with promoted productivity and decreased energy consumption.
Highlights
Electrochemical alcohols oxidation offers a promising approach to produce valuable chemicals and facilitate coupled H2 production
We expect that the MOOHs can cooperate with Au for alcohol oxidation reactions (AORs) at higher potential
Together with the Fourier transform infrared spectroscopy (FTIR) and electrochemical quartz crystal microbalance (EQCM) analysis, these results show that benzyl alcohol adsorption and enrichment is enhanced over Au/ CoOOH at the interface, which may contribute to its higher activity than that of Au
Summary
Electrochemical alcohols oxidation offers a promising approach to produce valuable chemicals and facilitate coupled H2 production. Tremendous efforts have been devoted to developing electrocatalysts with improved catalytic activities towards various oxidation reactions[8,9,10,11,12,13] Despite these efforts, the reported current density remains very low under moderate cell potential, for example, the electrooxidation of alcohols8,9, 5-hydroxymethyfurfural (HMF)[10,11], primary amines[12] and tetrahydroisoquinolines[13] are mostly operated at current density lower than 200 mA cm–2. The reported current density remains very low under moderate cell potential, for example, the electrooxidation of alcohols8,9, 5-hydroxymethyfurfural (HMF)[10,11], primary amines[12] and tetrahydroisoquinolines[13] are mostly operated at current density lower than 200 mA cm–2 This would hamper the overall efficiency and profitability for industrial production of value-added products coupled with H2 evolution that requires high current density. When the potential is further increased, the Au−OH species would be unavoidably oxidized to
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