Biomass-derived platform molecules offer a sustainable pathway for transitioning toward a circular bioeconomy. Isobutanol, a promising biofuel and versatile platform molecule, can be upgraded to isobutyric acid, an important chemical intermediate used in the plastics, pharmaceutical, and fragrance industries. However, conventional conversion routes rely on fossil-derived feedstocks and energy-intensive processes. In a study published in ENG. Chem. Eng. , researchers at Shandong University of Technology and Dalian University of Technology report a nickel-cobalt layered double hydroxide electrocatalyst that selectively converts isobutanol to isobutyric acid under ambient conditions.
The NiCo-LDH/NF catalyst was fabricated via a facile electrodeposition strategy on nickel foam substrates. SEM and TEM characterizations revealed a uniform three-dimensional hierarchical nanosheet structure. HRTEM showed clear lattice fringes with interplanar spacings of 0.26 and 0.23 nm, corresponding to the (012) and (015) planes of the LDH phase. XPS analysis revealed that Co incorporation shifted the Ni 2p peaks toward lower binding energies, indicating localized charge redistribution within the bimetallic hydroxide lattice. N₂ adsorption-desorption measurements showed that NiCo-LDH/NF possesses a higher specific surface area of 21.83 m²·g⁻¹ compared with 11.21 m²·g⁻¹ for Ni(OH)₂/NF and 6.19 m²·g⁻¹ for Co(OH)₂/NF.
Electrochemical evaluation showed that NiCo-LDH/NF exhibited significantly enhanced performance compared with monometallic hydroxide electrodes. The catalyst achieved a Faradaic efficiency of 91.3 % and selectivity of 93.2 % toward isobutyric acid at 1.52 V vs. RHE. The introduction of isobutanol reduced the anodic potential by approximately 200 mV at the same current density, indicating that isobutanol oxidation was more favorable than the competing oxygen evolution reaction. The Tafel slope of NiCo-LDH/NF was 75.25 mV·dec⁻¹, significantly lower than those of Ni(OH)₂/NF at 103.37 mV·dec⁻¹ and Co(OH)₂/NF at 121.88 mV·dec⁻¹. EIS revealed the lowest charge-transfer resistance for NiCo-LDH/NF at 1.10 Ω, compared with 8.78 Ω for Ni(OH)₂/NF and 12.29 Ω for Co(OH)₂/NF. The apparent activation energy for isobutanol oxidation over NiCo-LDH/NF was 58.56 kJ·mol⁻¹, lower than that of Ni(OH)₂/NF at 60.73 kJ·mol⁻¹ and significantly lower than that of Co(OH)₂/NF at 112.13 kJ·mol⁻¹.
In situ FTIR spectroscopy revealed that upon increasing applied potential, characteristic bands emerged at 1328, 1435, 1555, and 1672 cm⁻¹. The bands at 1435 and 1555 cm⁻¹ correspond to symmetric and asymmetric stretching vibrations of O＝C－O⁻ species, indicating carboxylate formation. The band at 1672 cm⁻¹ was assigned to the C＝O stretching vibration of adsorbed isobutyraldehyde intermediates. These spectral features support a sequential oxidation pathway from isobutanol to isobutyric acid via adsorbed isobutyraldehyde intermediates, with minor formic acid as a byproduct from limited C–C bond cleavage.
Long-term stability tests showed that NiCo-LDH/NF maintained FE and selectivity above 85.1 % and 89.9 %, respectively, after 24 h of operation. Post-stability characterization confirmed that the 3D nanosheet architecture was largely preserved without obvious structural collapse or compositional changes.
This work highlights the potential of bimetallic LDH electrocatalysts for selective upgrading of biomass-derived alcohols and sustainable waste-to-chemical conversions.
ENGINEERING Chemical Engineering
Experimental study
Not applicable
Electrocatalytic upgrading of biomass-derived isobutanol to isobutyric acid over NiCo layered double hydroxide nanosheets
29-Jun-2026