Anchoring hydroxyl intermediate on NiCo(OOH)_x nanosheets to enable highly efficient electrooxidation of benzyl alcohols

Abstract

Selective oxidation of alcohols to the carboxylic acid plays an important role in the production of valuable chemicals. Herein, NiCo hydroxide (NiCo(OOH) x ) nanosheets with a thickness of $4 nm were controllably fabricated in a facile way efficient for the electrooxidation of benzyl alcohol (BAL) to benzoic acid (BAD).Mechanistic studies confirmed the hydroxyl active intermediate ( OH*) generated on the surface of NiCo(OOH) x nanosheets through operando electrochemical impedance spectroscopy and the electron paramagnetic resonance spectroscopy analysis during the electrooxidation process. Importantly, we discovered that the OH* was crucial to boost the selective oxidation of BAL by attacking the hydroxyl end group to achieve carboxylic acid. The early onset potential of 1.16 V RHE in the presence of BAL was below 1.23 V RHE for oxygen evolution reaction.The rotating ring-disk electrode further revealed that the electrocatalytic BAL oxidation reaction occurred earlier in the oxygen evolution reaction. In 150 mM BAL, NiCo(OOH) x nanosheets generated a high BAD selectivity of >99% and full conversion of BAL in 3 h. The experimental and theoretical calculation revealed that the dominant pathway of BAL oxidation was the interaction between nucleophilic BAL with OH* to form BAL-OH* directly by dehydrogenates, thereby producing BAD with high efficiency. This research sheds mechanism insights on the electrocatalytic alcohols oxidation reaction.

Engineering Lattice Planes of NiCo-LDH Ultrathin Sheets for Boosting Methanol/Ethanol Oxidation Performance

“…Previous studies have evidenced that the unusual two-dimensional ultrathin wrinkled nanosheets contain abundant active sites and a larger specific surface area, which plays a critical role in the catalytic capabilities. , Besides, the thickness of the nanosheets was characterized by atomic force microscopy (AFM, Figures c and S2b). The results indicate that the thickness of nanosheets in NiCo-LDH-W and NiCo-LDH-E was about 1.92 and 1.18 nm (Figures S2c and d), which are smaller than that of the reported NiCo hydroxide (NiCo­( OOH ) x ) nanosheets (∼4 nm) . The above phenomenon confirms the ultrathin nanosheet properties of NiCo-LDH-W and NiCo-LDH-E.…”

Selective hydrogenation of benzoic acid over bimetallic NiCo embedded in N‐doped carbon

“…Cyclohexane carboxylic acid (CCA) is an essential and high value‐added intermediate for the manufacture of nylon‐6, photocuring agent 184 in addition to praziquantel, a medicine for the therapy of schistosomiasis 4,5 . The hydrogenation of benzoic acid (BA) is the most widely applied way to obtain CCA 6,7 . Combined with the biomass‐based synthesis of BA, 8,9 the BA selective hydrogenation has also gained continuing interest in biomass upgrading.…”

Water electrolysis for hydrogen production: from hybrid systems to self-powered/catalyzed devices

“…17g), confirming the formation of Co-containing nickel oxyhydroxide (Co-NiOOH) as the real active species. Co/Ni-based catalysts are commonly used for Ph-CH 2 OH oxidation, such as Mo-Ni alloy nanoparticle-modified MoO 2 , 243 h-Ni(OH) 2 , 344 Ni 2 P/NF, 350 NiCo 2 O 4 nanosheets, 351 b-NiOOH, 352 2D Ni-based MOFs, 353 plasma modified nickel foam, 354 Ni(OH) 2 nanosheet/Ni foam, 355 NiCo(OOH) x nanosheets, 356 Ni-Fe thin films, 357 Co-Ni LDH, 358 and Co 3 O 4 NPs/Ti. 359 The electrochemical synthesis reactions discussed earlier exclusively yield hydrogen at the cathode, while no gas is generated at the anode.…”