Ethylene glycol

Ethylene glycol (>99.5%) was purchased from Carl Roth, Germany. Sodium methoxide (MeONa) (95%) and cobalt acetate Co(OAc)₂ (>99.9%) were purchased from Sigma Aldrich, Darmstadt, Germany. Zinc acetate Zn(OAc)₂ (>99.9%) was purchased from Alfa Aesar, Kandel, Germany. HPLC grade, technical grade methanol, and isopropanol (rinsing agent) were purchased from VWR Darmstadt, Germany. Deuterated methanol for NMR analysis was purchased from Deutero, Kastellaun, Germany. Glass microfiber filters type GF/C and grade MN GF-1 were purchased from VWR, Darmstadt, Germany, and were used to filter PET residue and glycolysis product, respectively. Post-Consumer soft drink soda bottles were used as POSTC-PET waste sources. They were washed, cleaned, and crushed to use as a substrate as represented in Figure S1 (Supplementary Materials).

2.5 mmol of calcium chloride dihydrate (Sigma-Aldrich, ACS grade, >99%) were dissolved in 25 mL of ethylene glycol (>99%, Carl Roth) by ultrasonication (Elmasonic P, 80 kHz, 80% power, 40 °C, sweep mode) for 30 min. Then, a dispersion of 5 mmol sodium bicarbonate (Sigma-Aldrich, ACS grade, >99.7%) in ethylene glycol was added under stirring and the resulting dispersion was treated for 30 min by ultrasonication (80 kHz, 90% power, 40 °C, sweep mode)^{82 (link)}. The particles were isolated by centrifugation for 30 min at 7000 g and washed twice with Milli-Q water and once with ethanol (99.95%, VWR No. 20820.293). The product was stored in ethanol. ATR-FTIR characterization of the dried particles conformed to pure vaterite.

Manganese(II) acetate tetrahydrate (MnAc₂, >99%, pure) and ethylene glycol (EG, >99.5%, p.a.) were purchased from Carl-Roth. Tetraethylene glycol (TEG, 99%) was delivered by Sigma-Aldrich. For the electrode preparation, a 10 wt % Nafion^®/water solution was purchased from Sigma-Aldrich, analytical reagent-grade ethanol from Fisher Scientific, and Vulcan^® XC72R carbon powder was obtained from Cabot. For electrochemical measurements, reagent-grade lithium bis(trifluoromethylsulfonyl)imide (LiTFSI) was purchased from Merck KGaA and dimethyl sulfoxide (DMSO, anhydrous, ≥99.9%) from Sigma-Aldrich. All chemicals were used without further purification.

TiO₂ nanotubes (NTs) were grown on Ti foil (99.6 % purity, Advent, UK) in an organic electrolyte containing ethylene glycol (Carl Roth, Germany), 0.2 M ammonium fluoride (Carl Roth, Germany), and 2 M DI water (18.2 MΩ cm) at 70 V for 5, 7, 10, and 20 min at room temperature. The TiO₂ NTs were prepared by two‐step anodization in a two‐electrode O‐ring cell. Ti foil with a 1 cm² area was used as a working electrode, and Pt foil with a similar size was used as a counter electrode. The distance between the working and counter electrodes was set to 15 mm. After the first anodization step, the obtained TiO₂ NTs were ultrasonically removed, and the substrate was further used in the second anodization step. After the second anodization step, the sample was gently rinsed with DI water to remove excess electrolyte, followed by annealing in air at 450 °C for 1 h. The reference sample was prepared similarly but was immersed in ethanol for 36 h to remove remnants of the organic electrolyte. Afterward, the reference sample was annealed at 450 °C for 1 h in air.

The following chemicals with the indicated purities were used for the experiments. Ethylene carbonate (cEC, 99%) was obtained from Alfa Aesar (Haverhill, MA, USA). Ethylene glycol (99%) was obtained from Roth (Karlsruhe, Germany). Methanol (99.9%) was obtained from VWR (Dresden, Germany). Dichlormethan-D2 (99.5%) was obtained from Roth (Karlsruhe, Germany). Tichlormethan-D1 (99.8%) was obtained from Roth (Karlsruhe, Germany). Potassium phosphate tribasic anhydrous (99.5%) was obtained from VWR (Dresden, Germany). Sodium orthovanadate (V) (99.9%) was obtained from Alfa Aesar (Haverhill, MA, USA) and Potassium tin (IV) oxide trihydrate (95%) was obtained from Alfa Aesar (Haverhill, MA, USA).

Ethylene glycol (EG, ≥99.5%) and disodium
hydrogen phosphate dihydrate (≥98%) were purchased from Carl
Roth, hexenedioic acid (HA, >98%) from TCI, maleic acid (MA, 99%)
and sodium dihydrogen phosphate monohydrate (≥99.99%) from
Merck, N-tertbutyl benzothiazole sulfonamide (TBBS)
and 2,2-dibutyl diethylmalonate (98%) from abcr, methanol (≥99.8%),
dibutyl tin oxide (DBTO), 2,6-di-tert-butyl-p-cresol (BHT, 99%), and ¹³C₂–EG
(99 atom % ¹³C) from Sigma-Aldrich, and chloroform (≥99.8%)
from VWR. Deuterated solvents were obtained from Eurisotop and dried
over molecular sieves from Riedel-de Haën (0.4 nm). Pripol
1009 (dimer acid, DA, 98%) was kindly provided by Croda/Cargill.