Haucl4 3h2o

CMC (M.W. 250000) was purchased from Aladdin Industrial Corporation (Shanghai, China). Pb(NO₃)₂ and Cu(NO₃)₂·3H₂O were bought from Sinopharm Chemical Reagents Co., Ltd. (Beijing, China). AA (99.7%), UA, HAuCl₄·3H₂O (99.9%), GC, LA, Glu and dopamine hydrochloride were commercially obtained from Alfa Aesar (Beijing, China). IgG, anti-IgG and BSA (standard grade) were obtained from Xinjingke Biotechnology Co., Ltd. (Beijing, China). Clinical human serum samples were provided by Capital Normal University Hospital (Beijing, China). All other reagents were used as received. Deionized-distilled water was purified by Olst ultrapure K8 apparatus (Olst, Ltd., resistivity > 18 MΩ cm).

(3-Aminopropyl)trimethoxysilane (APTMS, 97%), sodium silicate solution (reagent grade), rhodamine 6G (95%), hydroxylamine hydrochloride (NH₂OH HCl, >98%) from Sigma-Aldrich; ammonia solution (28–30%) from VWR International; HAuCl₄·3H₂O (99.99% metals basis) from Alfa Aesar; trisodium citrate dihydrate (99%) from Acros Organics; hydrochloric acid (Emsure, 37%) from Merck. Before use, demineralized water was purified with a Milli-Q system (18.2 MΩ). All chemicals were used as received.

Gold (nominal 3% wt) was loaded on the xerogel supports by the colloidal method [30 (link),45 (link),46 (link),47 (link)], which consists of dissolving the gold precursor, HAuCl₄·3H₂O (Alfa Aesar, Karlsruhe, Germany), in water, adding polyvinyl alcohol (Aldrich, Darmstadt, Germany) and NaBH₄ (Aldrich), resulting in a ruby red solution to which the xerogel support was added under stirring. After a few days, the solution of CX started to lose colour, as Au was deposited on the support. The colourless solution was filtered, the catalyst washed thoroughly with distilled water until the filtrate was free of chloride and dried at 110 °C overnight. Solutions of CX-ox and CX-ox-Na took more time and even so the deposition was not complete (as found out later when the amount of gold present was determined), as these solutions never turned colourless. However, the same filtering and washing procedures were followed as with CX. The organic scaffold was removed from the supports by heat treatment under N₂ flow for 3 h at 350 °C (shown by elemental analysis to be efficient for this purpose), and then, the catalyst was activated by further treatment under hydrogen flow for 3 h also at 350 °C.

Mesityl oxide (abbrev. MesOx, 99.5%, Merck KGaA) for catalytic activity tests was stored in the Schlenk flask under He. MesOx for in situ FTIR spectroscopy experiments was additionally distilled under N₂ atmosphere and was stored in the Schlenk flask under only its own vapours (i.e. at a diminished pressure).
The following gases: H₂ (99.999%, Multax S.C.), He (99.999%, Multax S.C.), N₂ (99.999%, Multax S.C.), Ar (99.999%, Multax S.C.), 10%_vol H₂ in Ar (prepared by Multax S.C. from 99.999% purity gases), O₂ (99.999%, Multax S.C.) were used in all experiments.
In the catalysts syntheses the following materials were used: cerium dioxide (CeO₂, Austranal Praeparate), titanium dioxide (TiO₂, Aeroxide® P25), silica (SiO₂, Davison 62) hydrogen tetrachloroaurate(iii) trihydrate (HAuCl₄·3H₂O, 99.9%, Alfa Aesar), sodium borohydride (NaBH₄, 99%, Sigma-Aldrich), sodium hydroxide (NaOH, ppa, Chempur), 1,2-ethylenediamine (H₂NCH₂CH₂NH₂, will be abbreviated by “en”, ≥99.5%, Roth), diethyl ether ((CH₃CH₂)₂O, will be abbreviated by “Et₂O”, ppa, Chempur), propan-2-ol (ppa, Stanlab), 25% ammonia solution (NH_{3 aq}, ppa, POCH) and double-distilled water (also referred to as redistilled water).

HCl (37%), ethanol (99.8%), hexadecyltrimethylammonium bromide (CTAB, 98%), tetraethyl orthosilicate (TEOS, 99%), NaOH (98%), Rose Bengal (RB, 95%), TEMP (95%) and TEMPO (98%) were purchased from Sigma Aldrich and used as received. HAuCl₄·3H₂O (99.9%) and silver nitrate were purchased from Alfa Aesar, and ADPA (>98%) was obtained from Chemodex and l-methionine (Met, >99%) from TCI.