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Perovskite-related strontium orthoferrite, SrFeO3−δ, has been fluorinated by a low temperature reaction with poly(vinylidene fluoride) to give the compound SrFeO2F. X-ray powder diffraction shows that fluorination leads to an expansion of the unit cell which is consistent with partial replacement of oxygen by fluorine and consequent reduction in the oxidation state of iron. Magnetometry experiments in the temperature range 10–400 K showed small aligned moments (0.003 ± 0.000 05 μB per Fe3+ ion at 2 T and 300 K), indicating the absence of ferro- or ferrimagnetism. The 57Fe Mössbauer spectra recorded at temperatures below about 300 K show broadened, but unsplit, sextet patterns whilst spectra recorded above this temperature show clear splitting of the sextet structure and a magnetic ordering temperature of 685 ± 5 K. A model related to the pattern of substitution by fluorine on the octahedral arrangement of oxygen sites around iron is proposed in which SrFeO2F undergoes a magnetic transition at about 300 K from a low temperature state with random spin directions to an antiferromagnetic state.

Fluorination of the parent oxide, BaFeO 3-δ, with polyvinylidine fluoride gives rise to a cubic compound with a = 4.0603(4) Å at 298K. 57 Fe Mössbauer spectra confirmed that all the iron is present as Fe 3+. Neutron diffraction data showed complete occupancy of the anion sites indicating a composition BaFeO 2 F, with a large displacement of the Fe offsite. The magnetic ordering temperature was determined as T N = 645±5K. Neutron diffraction data at 4.2K established G-type anti-ferromagnetism with a magnetic moment per Fe 3+ ion of 3.95µ B . However, magnetisation measurements indicated the presence of a weak ferromagnetic moment, which is assigned to the canting of the antiferromagnetic structure. 57 Fe Mössbauer spectra in the temperature range 10 to 300K were fitted with a model of fluoride ion distribution that retains charge neutrality of the unit perovskite cell.

Lead halide perovskite solar cells are notoriously moisture-sensitive, but recent encapsulation strategies have demonstrated their potential application as photoelectrodes in aqueous solution. However, perovskite photoelectrodes rely on precious metal co-catalysts, and their combination with biological materials remains elusive in integrated devices. Here, we interface [NiFeSe] hydrogenase from Desulfovibrio vulgaris Hildenborough, a highly active enzyme for H 2 generation, with a triple cation mixed halide perovskite. The perovskite−hydrogenase photoelectrode produces a photocurrent of −5 mA cm −2 at 0 V vs RHE during AM1.5G irradiation, is stable for 12 h and the hydrogenase exhibits a turnover number of 1.9 × 10 6 . The positive onset potential of +0.8 V vs RHE allows its combination with a BiVO 4 water oxidation photoanode to give a self-sustaining, bias-free photoelectrochemical tandem system for overall water splitting (solar-to-hydrogen efficiency of 1.1%). This work demonstrates the compatibility of immersed perovskite elements with biological catalysts to produce hybrid photoelectrodes with benchmark performance, which establishes their utility in semiartificial photosynthesis.

A series of copolymers comprising a terpyridine ligand and various functional groups were synthesized toward integrating a Co‐based molecular CO2 reduction catalyst. Using porous metal oxide electrodes designed to host macromolecules, the Co‐coordinated polymers were readily immobilized via phosphonate anchoring groups. Within the polymeric matrix, the outer coordination sphere of the Co terpyridine catalyst was engineered using hydrophobic functional moieties to improve CO2 reduction selectivity in the presence of water. Electrochemical and photoelectrochemical CO2 reduction were demonstrated with the polymer‐immobilized hybrid cathodes, with a CO:H2 product ratio of up to 6:1 compared to 2:1 for a corresponding “monomeric” Co terpyridine catalyst. This versatile platform of polymer design demonstrates promise in controlling the outer‐sphere environment of synthetic molecular catalysts, analogous to CO2 reductases.

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2We have investigated the electronic and magnetic properties of the mixed oxide α-

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