The direct synthesis of H2O2 from molecular H2 and O2 over AuPd catalysts, supported on TiO2 and prepared via an excess chloride co-impregnation procedure is investigated. The role of Au:Pd ratio on the catalytic activity towards H2O2 formation and its subsequent degradation is evaluated under conditions that have previously been found to be optimal for the formation of H2O2. The combination of relatively small nanoparticles, of mixed Pd-oxidation state is shown to correlate with enhanced catalytic performance. Subsequently, a detailed study of catalytic activity towards H2O2 synthesis as a function of AuPd loading was conducted, with a direct correlation between catalytic activity and metal loading observed. Graphic Abstract

The combination of an evolved unspecific peroxygenase (UPO), from Agrocybe aegerita (PaDa-I variant) and bimetallic Pd-based catalysts, is demonstrated to be highly effective for the one-pot oxidative valorization of cyclohexane to cyclohexanol and cyclohexanone (collectively KA oil), via the in situ formation of H 2 O 2 from the elements. The alloying of Pd with Zn in particular is found to significantly enhance catalytic performance compared to bimetallic PdAu or monometallic Pd analogues. The improved activity of the PdZn/TiO 2 /PaDa-I system is attributed to the facile formation of PdZn alloys and the resulting electronic modification of Pd, which results in an inhibition of competitive chemo-catalyzed H 2 O 2 degradation reactions and the total suppression of the overoxidation of cyclohexanol. By comparison, the large population of Pd-only clusters present in both the PdAu and monometallic Pd catalysts is considered to be responsible for the promotion of further oxidation products and the unselective conversion of H 2 O 2 to H 2 O, which hampers overall process efficiency. Notably, given the susceptibility of the enzyme to deactivation at moderate H 2 O 2 concentrations, the continual supply of low levels of the oxidant via in situ production represents a highly attractive alternative to the continuous addition of preformed H 2 O 2 or co-enzyme-based systems.

The combination of heterogeneous catalysis and biocatalysis into one-pot reaction cascades is a potential approach to integrate enzymatic transformations into existing chemical infrastructure. Peroxygenases, which can achieve clean C-H activation,...

The introduction of dopant concentrations of Pt into supported AuPd nanoparticles, when used in conjunction with an evolved unspecific peroxygenase (UPO) from Agrocybe aegerita (PaDa-I) is demonstrated to offer high efficacy towards the one-pot selective oxidation of cyclohexane to KA oil (cyclohexanol and cyclohexanone), via the in-situ synthesis of H 2 O 2 . The optimised AuPdPt/TiO 2 /PaDa-I system achieves significant improvements over analogous AuPd or Pd-only formulations or the use of commercially available H 2 O 2 , with this attributed to the increased rate of H 2 O 2 production by the chemo-catalyst, which results from the electronic modification of Pd species via Pt incorporation, upon the formation of trimetallic nanoalloys.