Methanal

Acetic acid (purity, ≥ 99.5%), chloroform (purity, ≥ 99.0%), ethanol (purity, ≥ 99.7%), xylene (purity, ≥ 99.0%), methanal (purity, ≥ 36.0%), hematoxylin-eosin solution, neutral gum, were purchased from Sinopharm Chemical Reagent ltd. (Shanghai, China), HE dye solution set, were purchased from Solarbio corporation (Beijing, China). All chemicals and reagents were of analytical grade.

Chloroplatinic acid (H₂PtCl₆·6H₂O, AR, Pt > 37.5%), copper nitrate (Cu(NO₃)₂·3H₂O, AR, 99%), iron nitrate (Fe(NO₃)₃·9H₂O, AR), methanal (CH₂O, AR), potassium permanganate (KMnO₄, ≥99.5%), sodium hydroxide (NaOH, ≥96%), and aqueous hydrogen peroxide solution (H₂O₂, AR, H₂O₂ being 30 wt%) were provided by Sinopharm Chemical Reagent Co, Ltd. Imidazolidinyl urea (C₁₁H₁₆N₈O₈, AR, 98%) was provided by Aladdin Reagent (Shanghai) Co, Ltd. Alumina (Al₂O₃) particles were provided by Yantai Henghui Chemical Co, Ltd. SiO₂ (20–40 mesh) particles were provided by Qingdao Ocean Chemical. Activated carbon (20–40 mesh) was provided by FuJian Xinsen Carbon Co, Ltd. All chemicals were of analytical purity and used without further treatment. Deionized (DI) water was applied for the whole experiment.

Sodium tungstate dehydrate (Na₂WO₄·2H₂O, 99.5%), sodium tetrachloropalladate(ii) (AR), citric acid (CA, >99.5%), d-(+)-glucose (AR), hydrochloric acid (36–38%, AR) and liquid chemicals (including methanal, methanol, ethanol, aqua ammonia, acetone, toluene, and n-hexane) were purchased from Sinopharm Chemical Reagent Co. Ltd, China. All reagents used in our experiments were of analytical grade and used without further purification.