Co3o4

Si-incorporated perovskite samples were prepared by a ball-milling-assisted solid-state reaction approach. Freshly dried chemicals of SrCO₃, Co₃O₄ and SiO₂ (Sigma-Aldrich) were weighted according to the stoichiometric ratio of SrCo_1–ySi_yO_3–δ (y = 0.00, 0.03, 0.05, 0.07 and 0.10) with different intentional Si-doping levels. The precursory powders were then mixed in an acetone medium for 1 h using a high-energy ball mill (Planetary Mono Mill, Pulverisette 6, Fritisch) at a rotation of 400 rpm. The as-obtained mixtures were dried, pressed into pellets and subjected to calcination in air under ambient pressure at 1000–1200 °C for 24 h with intermediate grindings. The actual composition of each sample after calcination was analysed by XRD (Supplementary Tables 1 and 2).

Particles used in this study were crystalline silica DQ12 (SiO₂, d50 = 2.2 µm; DMT, Essen, Germany); crystalline Min-U-Sil^® 5 (d50 = 1.6 µm, US Silica Company, Berkeley Springs, West Virginia, USA); monodisperse silica spheres (MSS, d50 = 1 µm, Fiber Optic Center Inc., New Bedford MA, USA); and nanosized silica (Aerosil OX50 and FK 320, respectively 40 nm and 15 nm, Evonik, Degussa, Frankfurt AM, Germany), carbon black (CB, ultrafine, d50 = 35 nm, ENSACO 250G, Timcal), carbon nanotubes (CNT/CNT-7/MWCNT-7, d = 75 nm, L = 7.1 µm, Mitsui, Tokyo, Japan), asbestos (crocidolite, d = 200 nm, L = 3 µm, UICC, Geneva, Switzerland), tungsten carbide (WC, d50 < 1 µm; Johnson Matthey, Royston, United Kingdom) and cobalt oxide (Co3O4, d50 < 10 μm, Sigma Aldrich, St. Louis, Missouri, USA, now part of Merck). To sterilize and inactivate any trace of endotoxin, particles were heated at 200 °C for 2 h.

Co(NO₃)₂ ⋅6H₂O (≥99.999 %), Co₃O₄ (99.99), CoO (99.99 %), LiCoO₂ (>99.8 %), Mn(NO₃)₂ ⋅4H₂O (≥99.99 %), Mn(SO₄)₂⋅xH₂O (99.99), MnO₂ (≥99 %), Mn₃O₄ (≥97 %), Mn₂O₃ (≥99.9 %), L‐(+)‐Tartaric acid (≥99.5 %) and (2 M and 0.1 M) NaOH solutions were ordered from Sigma‐Aldrich. Graphite foil (≥99.8) with a thickness of 0.254 mm ordered from VWR. All reactants were used as received, without any further treatment. Solutions were prepared with deionized water (>18 MΩ cm).

The
alloys were prepared through the SPS
method. The compositions of the alloys were determined by adjusting
the relative fraction of the components in the precursor powders (Co₃O₄ (Sigma-Aldrich, <10 μm), Cr₂O₃ (Sigma-Aldrich, ≥98%), Fe₂O₃ (KeBo, no more information was given), MnO (Sigma-Aldrich, 60 mesh,
99%), and NiO (Sigma-Aldrich, 325 mesh, 99%)). The powders were manually
ground for 10 min. After that, the powders were placed in a 14 mm-diameter
graphite die and sintered via SPS (SPS-211Lx SPS Dr. SINTER LAB Jr.
SERIES, Fuji Electronic Industrial) under a uniaxial pressure of 38
MPa under vacuum (1.6 × 10¹ Pa). A series of samples
were synthesized by varying the temperature from 1200 to 1300 °C
during SPS, labeled according to Table 1. The highest temperature during the process was chosen
below the melting temperature of almost all reagents. One of the precursors,
Co₃O₄, has a melting point of 895 °C. This
oxide is the mix of two oxides CoO and Co₂O₃. An important note is that the melting temperature (Table S1) for the precursors can be lower in
vacuum and under pressure. To prevent the leakage of the sample around
the melting point of Co₂O₃, an additional step
was added to the procedure waiting point around 850 °C. One of
the samples (H1) was synthesized with a predrying step to identify
if the presence of water molecules affects the SPS. Predrying was
done at 85 °C for 15 min.

Commercially available metal oxides of lead (Sigma-Aldrich, PbO, ACS reagent ≥ 99.0% #402982), copper (Sigma-Aldrich, CuO, powder <10 μm, 98% #208841), nickel (Sigma-Aldrich, NiO, 325 mesh, 99% #399523), zinc (Sigma-Aldrich, ZnO, ACS Reagent ≥ 99.0%, #96479) and cobalt (Sigma-Aldrich, Co₃O₄ powder <10 μm #221643) were used in soil dosing experiments. When necessary oxides were finely ground to a powder using a mortar and pestle. Once ground, oxides were placed on plastic weigh boats in a sealed glass container with an open beaker of nitric acid. Oxides were left in contact with acid vapours for 48 hours to remove any carbonates and subsequently, air dried in a fume hood for 24 hours. Dried metal oxides were then individually weighed at the appropriate concentration for each metal mixture ratio and added to dry soil. Once all metal oxides were added, soils were thoroughly mixed by stirring and shaking and soil water content was adjusted to 50% water holding capacity.

Lithium carbonate (Li₂CO₃), potassium superoxide (KO₂), lithium bis(trifluoromethane)sulfonamide (LiTFSI), 9,10-dimethylanthracene (DMA), and Co₃O₄ were purchased from Sigma-Aldrich. Li₂¹³CO₃ and ¹³C were purchased from the Cambridge Isotope Ltd. Tetraethylene glycol dimethyl ether (tetraglyme), ethylene carbonate (EC), and methyl ethyl carbonate (EMC) were purchased from the TCI Chemical. Tetraglyme was distilled under vacuum and dried with activated molecular sieves (4 Å). Lithium hexafluorophosphate (LiPF₆), ferrous sulfate (FeSO₄), phosphoric acid (H₃PO₄), acetic acid, and hydrogen peroxide (H₂O₂) were purchased from Aladdin. Lithium iron phosphate (LFP) was purchased from Shenzhen Betterui New Materials Group Co., Ltd. Dimethyl sulfoxide-d₆ (DMSO-d₆) and 18-crown-6 were purchased from the Shanghai Yuanye Bio-Technology. Argon (N5 grade) and10 % Ar-O₂ (N5 grade) were obtained from Nanjing Special Gas Ltd. Polytetrafluoroethylene emulsion (PTFE) was purchased from Innochem. Celgard separator (25 μm thickness, Celgard), glass fiber separator (GF/F, Whatman), and Super P carbon (Timcal) were purchased from Duoduo Chemical Technology Co. Ltd.

Both SCI and SSI were synthesized with the solid-state reaction. Stoichiometric amounts of SrCO₃ (99.9%; Sigma-Aldrich), IrO₂ (99.9%; Sigma-Aldrich), Co₃O₄ (Sigma-Aldrich), and Sc₂O₃ (99.9%; Sigma-Aldrich) were thoroughly ground and calcined at 1150°C (for SCI) or 1350°C (for SSI) for 12 hours under ambient air.