Renewable H₂ production emerges as a forward-looking technology towards green energy transition. Herein, we present a study on novel multimetallic nano-oxides used as co-catalysts for H₂ production via HCOOH dehydrogenation (FADH) by an Fe^II(Polyphosphine) molecular catalyst, under near-ambient P, T conditions. The co-catalyst nano-oxides consist of multimetallic {LaSrCrFeO} and {LaSrCrFeVO} perovskites, produced by flame spray pyrolysis (FSP) technology. Kinetic catalytic H₂ evolution data show that both {LaSrCrFeO} and {LaSrCrFeVO} significantly boost H₂ via co-catalytic action. Arrhenius analysis reveals that they decrease the rate-limiting activation energy, E_a. Specifically, E_a = 77.4 kJ mol⁻¹ of {Fe²⁺/PP₃} catalyst is decreased to E_a = 67.8 kJ mol⁻¹ in {LaSrCrFeO + Fe²⁺/PP₃} and E_a = 56.2 kJ mol⁻¹ in {LaSrCrFeVO + Fe²⁺/PP₃} catalyst. These significant thermodynamic effects are not observed when the simple parental oxides are used. The present findings are discussed in the context of a boosting role {LaSrCrFeO} and {LaSrCrFeVO} to the key catalytic intermediates of the Fe^II(Polyphosphine) catalyst. Technology-wise, this work exemplifies a novel strategy for the industrial production of co-catalysts using FSP technology within the in-situ H₂ production landscape.

The development of durable heterogenized molecular catalysts based on earth-abundant metals remains a key challenge for sustainable Η2- production via Formic Acid Dehydrogenation (FADH), due to catalyst deactivation during prolonged operation. Herein, robust {SiO2–triazine}@[PNP-Fe] heterogeneous catalysts were developed via covalent immobilization of molecular [Fe– Pincer PNP], catalyst on a {SiO2–triazine} support. The catalytic performance was fine-tuned by incorporation of a PP₃-phosphine as co-ligand, therefore the {SiO2–triazine}@[PNP-Fe]/ PP₃} hybrid system combined the activity of homogeneous catalysts with the robustness and recyclability of heterogeneous systems. Two PNP-immobilization strategies, and two Pincer-PNP ligands, iProPNP and tBuPNP with different steric properties, were systematically investigated to establish structure–performance relationships. Among the prepared materials, the directly-immobilized {SiO2–triazine}@[iProPNP-Fe]/PP₃} catalyst exhibited the highest FADH activity, producing 86.4 L of H₂/CO₂, achieving a total turnover number of 235,535. This hybrid shows significant robustness maintaining FADH-catalytic activity for 61 h over two consecutive cycles. Mechanistic studies revealed that catalyst deactivation is governed primarily by gradual depletion and protonation of the mobile PP₃ co-ligand, rather than degradation of the {SiO2–triazine}@[PNP-Fe] catalyst. Guided by this finding, periodic PP₃ replenishment was implemented as an operational strategy that continuously regenerated catalytically active Fe-species and significantly prolonged catalyst lifetime for >60h. These findings establish {SiO2–triazine} hybrid materials as robust platform for heterogenized molecular Fe catalysts and demonstrate that dynamic co-ligand management provides a general strategy for extending the lifetime of immobilized molecular catalysts.