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Current catalysis undergoes a paradigm shift from molecular and heterogeneous realms towards new dynamic catalyst concepts. This calls for innovative strategies to understand the essential catalytic motifs and true catalysts emerging from oxidative transformation processes. Polyoxometalate (POM) clusters offer an inexhaustible reservoir for new noble metal-free catalysts and excellent model systems whose structure–activity relationships and mechanisms remain to be explored. Here, we first introduce a new {ZnnNa6−n(B-α-SbW9O33)2} (n = 3–6) catalyst family with remarkable tuning options of the Zn-based core structure and high activity in H2O2-assisted catalytic alcohol oxidation as a representative reaction. Next, high level solution-based computational modelling of the intermediates and transition states was carried out for [Zn6Cl6(SbW9O33)2]12− as a representative well-defined case. The results indicate a radical-based oxidation process with the involvement of tungsten and adjacent zinc metal centers. The {ZnnNa6−n(B-α-SbW9O33)2} series indeed efficiently catalyses alcohol oxidation via peroxotungstate intermediates, in agreement with strong spectroscopic support and other experimental evidence for the radical mechanism. Finally, the high performance of [Zn6Cl6(SbW9O33)2]12− was traced back to its transformation into a highly active and robust disordered Zn/W-POM catalyst. The atomic short-range structure of this resting pre-catalyst was elucidated by RMC modelling of the experimental W-L3 and Zn-K edge EXAFS spectra and supported with further analytical methods. We demonstrate that computational identification of the reactive sites combined with the analytical tracking of their dynamic transformations provides essential input to expedite cluster-based molecular catalyst design. [ABSTRACT FROM AUTHOR]

Transition metal carbodiimides MNCN (M = Co, Ni, Co0.9Ni0.1, Mn and Cu), were studied by simultaneous operando Raman and X-ray absorption spectroscopy (XAS) with focus on surface oxide detection during electrocatalytic water oxidation. As a proof of concept, easily modifiable screen-printed electrodes were used in this unified operando synchrotron setup for a trade-off between convenience of electrochemical anodization and spectroscopic data acquisition. Monitoring of chemical and structural transformations at the electrode surface during initial anodic electrode polarization shows stability for MNCN with M = Co, Ni, Co0.9Ni0.1 and Mn. While MnNCN is inactive, CoNCN emerges as the most active representative of the series. CuNCN displays pronounced side reactions and the formation of a surface copper oxide layer leading to lower current density attributed to water oxidation, as evident from an irreversible variation of the CuNCN redox behaviour in rotating ring-disc voltammetry. Furthermore, the accompanying structural and vibrational spectroscopy properties of the different MNCN compounds were explored with complementary ex situ analytical methods. [ABSTRACT FROM AUTHOR]