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. 2025 Nov 28;16(1):10766.
doi: 10.1038/s41467-025-65807-8.

Microbial-vulcanized organic-inorganic dual-modulated cobalt hydroxide for oxygen evolution reaction

Jia Zhang #  1 , Lu-Yao Guo #  1 , Xiao-Qian Lin #  1 , Gui-Hua Wen #  1 , Xue-Feng Zhang  1 , Li-Hong Yu  1 , Mei-Qian He  1 , Yu-Mei He  1 , Long Zou  1 , Meng-Tian Zhang  1 , Li-Ming Cao  1 , Chun-Ting He  2
Affiliations

Microbial-vulcanized organic-inorganic dual-modulated cobalt hydroxide for oxygen evolution reaction

Jia Zhang et al. Nat Commun. .

Abstract

Developing efficient chemical modification technologies for upgrading classic non-noble metal based electrocatalysts to further meet the demands of practical water electrolysis industry is of vital challenge. Here, we propose an organic-inorganic dual-modulation strategy to construct a cobalt hydroxide-based electrocatalyst, MEC-17, synthesized by an eco-friendly and facile microbial-mediated vulcanization method. This electrocatalyst, modified with both 2-methylimidazole and inorganic sulfur exhibits notable oxygen evolution reaction performance, achieving an overpotential of 285.6 ± 1.7 mV and exceeding 300 h of durability at a high current density of 1000 mA cm-2. The operando characterizations and theoretical calculations reveal that sulfur dopant primarily shortens the Co-Co distances to support oxide path mechanism, while 2-methylimidazole plays a more critical role by modulating the d-band center of the Co sites, which optimizes intermediate adsorption for ensuring efficient O-O coupling. This work offers insights into the design of organic-inorganic hybrid electrocatalysts and contributes to understanding the origin of their electrocatalytic activities.

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Conflict of interest statement

Competing interests: The authors declare no competing interests.

Figures

Fig. 1
Fig. 1. Catalyst engineering through distinct doping strategies.
a Inorganic heteroatom doping induces lattice strain and electronic structure modification. b Organic ligand modification enables strong electronic regulation. c Synergistic effects of organic-inorganic dual-modification for both significantly changing the geometric and electronic structures of active metal atoms. Red and blue shadows denote electron gain and loss, respectively, with color depth indicating the extent of change.
Fig. 2
Fig. 2. Molecular vulcanization and morphology characterizations.
a Schematic illustration of the microbial vulcanization of ZIF-67 to synthesize MV-S/Co(OH)2/MI. b SEM image of microbial cells and MV-S/Co(OH)2/MI. c PXRD monitoring of ZIF-67 by microbial vulcanization under different times. d SEM and sample photos of the transitions from ZIF-67 to MV-S/Co(OH)2/MI using different vulcanizing time (the scale bars are 400 nm). e Double aberration-corrected HAADF-STEM image (inset: metal arrays of Co(OH)2 lattice), f AFM (inset: thickness profile), and g elemental mapping images of MV-S/Co(OH)2/MI. h Photograph of MV-S/Co(OH)2/MI laboratory preparation process. i The MV-S/Co(OH)2/MI obtained by one lab-scale preparation. j Plates (LMEC represents Lab of Molecule-based Energy Chemistry) marked with bacteria after vulcanization of ZIF-67. Source data are provided as a Source Data file.
Fig. 3
Fig. 3. Catalyst components and structures.
a Comparison of synthesis conditions and sample colors, b the MS and 1H-NMR spectra, c Raman spectra, d the Co, S and N contents, and e FT-IR spectra of MV-S/Co(OH)2/MI, MV-S/Co(OH)2, MV-Co(OH)2/MI, and S/ZIF-67, respectively. f TG-MS curves for the thermal decomposition of MV-S/Co(OH)2/MI. g Co 2p XPS spectra of catalysts. Source data are provided as a Source Data file.
Fig. 4
Fig. 4. Electrocatalytic activity evaluation.
a OER polarization curves of catalysts on GCE in O2-saturated 1.0 M KOH (pH = 13.6 ± 0.2) under 25 °C at a scan rate of 5 mV s−1. b Comparison of overpotentials, Tafel slopes, Cdl, Rct and mass activities of catalysts. c LSVgeo curves of MV-S/Co(OH)2/MI on different substrates (inset: summary of overpotentials of MV-S/Co(OH)2/MI on different substrates at 0.1, 0.5, and 1.0 A cm−2. Error bars represent standard deviation, n = 3 independent replicates.). d The AEMWE activities of Pt/C||MV-S/Co(OH)2/MI and commercial Pt/C||IrO2 catalysts. Polarization curves of the electrolyzer without iR-compensation 1.0 M KOH (pH = 13.6 ± 0.2) solution at 25 °C. e Overpotential comparison of MV-S/Co(OH)2/MI and reported advanced Co-based electrocatalysts on different substrates at 10 mA cm−2 in 1.0 M KOH. f Consecutive chronoamperometric test of the AEMWE using Pt/C||MV-S/Co(OH)2/MI were conducted at a potential of 2.0 V in 1.0 M KOH (inset: photograph and assembly schematic of the AEMWE device). Source data are provided as a Source Data file.
Fig. 5
Fig. 5. Investigation of OER catalytic pathway.
a Operando Raman spectra of MV-S/Co(OH)2/MI during OER electrocatalysis. b Co K-edge XANES profiles, and c Fourier transform EXAFS of MV-S/Co(OH)2/MI, MV-S/Co(OH)2, MV-Co(OH)2/MI, and Co(OH)2 after OER. d Potential-dependent operando ATR-SEIRAS of MV-S/Co(OH)2/MI. e DEMS signals of 36O2 products for 18O-surface-labeled MV-S/Co(OH)2/MI and Co(OH)2 tested in the electrolyte using H216O as solvent. f Polarization curves of MV-S/Co(OH)2/MI with or without TMA+. g Polarization curves of MV-S/Co(OH)2/MI in the electrolytes utilizing H2O and D2O as solvents, respectively. Inset shows the dependence of KIEs value on overpotential. Source data are provided as a Source Data file.
Fig. 6
Fig. 6. Synergistic mechanism of the organic-inorganic dual dopants.
Optimal conformations of a Co(OH)2 and, b MV-S/Co(OH)2/MI for key intermediates in the reaction pathways of OPM (green arrow) and AEM (blue arrow). c Comparisons of the energy barriers at the OPM pathway for the catalysts. d Quantitative relation between ΔGO*−O* and the d-band center of Co in different catalysts. The area of the circle represents the current density of different catalysts at an overpotential of 0.3 V. e Electron density difference fields for the S doped, MI doped, and S, MI co-doped Co(OH)2. The yellow and blue regions indicate electron depletion and accumulation, respectively, isovalue = 0.04. f The interatomic Co−Co distances in Co(OH)2 (I), MV-Co(OH)2/MI (II), MV-S/Co(OH)2 (III), and MV-S/Co(OH)2/MI (IV). Color codes: dark blue, Co; pink, O; yellow, S; gray, C; green, N; white, H. Source data are provided as a Source Data file.
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