Alcohols electrooxidation coupled with H2 production at high current densities promoted by a cooperative catalyst

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.

Selective Electrooxidation of Biomass‐Derived Alcohols to Aldehydes in a Neutral Medium: Promoted Water Dissociation over a Nickel‐Oxide‐Supported Ruthenium Single‐Atom Catalyst

“…This phenomenon may be associated with the higher activity of π‐bond‐containing alcohols (in terms of potential at 1 mA cm −2 , Figure S30f), and the competition between alcohol oxidation and aldehyde oxidation during the electrocatalytic BDAOR. Our recent work suggested that alcohols with π bond, such as benzyl alcohol and β‐phenylethanol, are more active than the alcohols without π bond, because the energy levels of the highest occupied molecular orbital (HOMO) for π‐bond‐containing alcohols are higher, which means that these alcohols are more likely to be oxidized [52] . The higher activity of π‐bond‐containing alcohol reactant would enable a more favorable kinetics of alcohol oxidation than aldehyde oxidation, and thus suppresses the further oxidation of aldehyde product during electrocatalysis, finally leading to a higher yield of aldehyde product.…”

A bimetallic synergistic effect on the atomic scale of defect-enriched NiV-layered double hydroxide nanosheets for electrochemical phenol hydroxylation

“…Then the intermediate state of dihydroxybenzenes was oxidized by V 5+ to hydroquinone or catechol in the proton transfer process. 50,51 As the reaction proceeded, a small amount of HQ was overoxidized to form p -benzoquinone (Fig. 8b III).…”

Earth‐Abundant Metal‐Based Electrocatalysts Promoted Anodic Reaction in Hybrid Water Electrolysis for Efficient Hydrogen Production: Recent Progress and Perspectives

“…One of the oxidation products, benzoic acid (BAc), with high value, can serve as a versatile intermediate in manufacturing flavor ingredients and cosmetical preservatives. According to the literature, the electrooxidation of BA into BAc possesses a lower thermodynamical potential than that of OER, [103,104] thus, the benzyl alcohol oxidation reaction (BAOR) also has been employed in HWE for highly efficient H 2 production with concurrent BAc (or in the form of salt) production in alkaline media lately. Sun's group firstly used the 3D porous nickel framework (hp-Ni) as a bifunctional electrocatalyst for the refining of BA and other aromatic alcohols (e.g., 4-nitrobenzyl alcohol, 4-methylbenzyl alcohol) integrated with the HER under alkaline condition.…”