| X-ray diffraction | Monoclinic phase |
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| Scanning electron microscopy | Porous, worm-like morphology with a uniform thickness of ~700–800 nm |
Jie Ouyang, Bing-hao Wang, Yixin Zhang, Yunsheng Li, Yujie Ren, Simiao Zhou, Xiangyi Fu, Huijuan Hu, Qian Zhang, Jiamin Wu, Xihui Zhu, Sheng Shen, Shuang-Feng Yin. “Carbonate-mediated adsorption switching enables alkaline current multiplication in glycerol oxidation on BiVO₄.” ChemRxiv (). https://doi.org/10.26434/chemrxiv.15007714/v1
Values presented only in analytical plots and micrographs were not transcribed. The main paper refers to supporting information, but no separate supporting information file was found among the files available from the ChemRxiv record
| Electron paramagnetic resonance spectroscopy | DMPO–•OH signals were enhanced in Na₂CO₃ relative to Na₂SO₄; adding glycerol to the carbonate solution quenched the •OH signal and gave rise to carbon-centered radical signals |
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| X-ray photoelectron spectroscopy, 0.5 M Na₂CO₃ treatment for 12 h relative to 0.5 M Na₂SO₄ treatment | Negative binding-energy shifts of 0.4 eV for Bi 4f, 0.3 eV for V 2p, and 0.4 eV for lattice oxygen O 1s |
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| X-ray photoelectron spectroscopy, high-concentration Na₂SO₄ treatment | Marginal Bi 4f shift of 0.1 eV and no detectable V 2p shift |
| Contact angle, untreated BiVO₄ | 42° |
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| Contact angle, BiVO₄ after 5 min in 0.5 M Na₂CO₃ and 1 mM sodium laurate | ~42° |
| Contact angle, BiVO₄ after 5 min in 0.5 M Na₂SO₄ and 1 mM sodium laurate | 141° |
| Contact angle, Bi₂O₃ after 5 min in 1 mM sodium laurate | 18° → 150° |
| Contact angle, V₂O₅ after 5 min in 1 mM sodium laurate | 14° → 15° |
| Contact angle, Bi₂O₃, 0.5 M Na₂SO₄ at pH 10 | 121° |
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| Contact angle, BiVO₄, 0.5 M Na₂SO₄ at pH 10 | 121° |
| Contact angle, Bi₂O₃, 0.5 M Na₂SO₄ at pH 2 | 66° |
| Contact angle, BiVO₄, 0.5 M Na₂SO₄ at pH 2 | 94° |
| Contact angle, Bi₂O₃, 0.5 M Na₂CO₃ at pH 10 | 22° |
| Contact angle, BiVO₄, 0.5 M Na₂CO₃ at pH 10 | 40° |
| Open-circuit potential upon glycerol addition | Substantially larger negative shift in Na₂CO₃ than in Na₂SO₄ |
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| In situ electrochemical impedance spectroscopy, Bode phase | Initial decrease followed by an increase in phase angle in both electrolytes; the phase angle dropped more steeply at low overpotentials in Na₂CO₃, and the transition to increasing phase angle occurred at ~0.4 V vs. RHE, earlier than in Na₂SO₄ |
| In situ ATR-IR under illumination | C=O stretching bands appeared earlier and with greater intensity in Na₂CO₃ than in Na₂SO₄; the C=O peak was redshifted from 1723 cm⁻¹ in sulfate to 1715 cm⁻¹ in carbonate; the 1339 cm⁻¹ band, assigned to νₛ(O–C=O) of surface carboxylate species, emerged earlier and grew more strongly in Na₂CO₃ |
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| UV–Vis absorption spectroscopy, Na₂CO₃ and Na₂SO₄ electrolytes | Glycerol, formate, and glycolate showed negligible V⁵⁺ reduction in either electrolyte; glyceraldehyde, dihydroxyacetone, and glycolaldehyde readily reduced V⁵⁺ in carbonate with comparable kinetics; in sulfate, glyceraldehyde and dihydroxyacetone reduced V⁵⁺ at significantly slower rates and glycolaldehyde was essentially unreactive |
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| X-ray diffraction | Characteristic peaks of monoclinic WO₃, JCPDS No. 43-1035, and monoclinic BiVO₄, JCPDS No. 14-0688; no impurity peaks observed |
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| Scanning electron microscopy | Well-aligned WO₃ nanoplate scaffold conformally coated with a BiVO₄ overlayer; rough interface with the two components in close contact |
| Cross-sectional energy-dispersive X-ray spectroscopy mapping | W mainly distributed in the underlying scaffold and Bi/V enriched in the upper porous region, with spatial overlap near the interface |
| Electrochemical impedance spectroscopy under front illumination | Charge-transfer resistance approximately 69.9 Ω, compared with approximately 457.9 Ω for pristine BiVO₄ |
| Electrochemical impedance spectroscopy under back illumination | Charge-transfer resistance approximately 108.7 Ω, compared with approximately 167.2 Ω for pristine BiVO₄ |