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Graphitic carbon nitride (g-C 3 N 4 ) is known to photogenerate hydrogen peroxide in the presence of hole quenchers in aqueous environments.Here, the g-C 3 N 4 photocatalyst is embedded into a host polymer of intrinsic microporosity (PIM-1) to provide recoverable heterogenized photocatalysts without loss of activity. Different types of g-C 3 N 4 (including

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Photo-generated high-energy surface states can help to produce chlorine in aqueous environments. Here, aligned rutile (TiO2) nanocrystal arrays are grown onto fluorine-doped tin oxide (FTO) substrates and activated either by hydrothermal Sr/Ba surface doping and/or by vacuum-annealing. With vacuum-annealing, highly photoactive films are obtained with photocurrents of typically 8 mA cm−2 at 1.0 V vs. SCE in 1 M KCl (LED illumination with λ = 385 nm and approx. 100 mW cm−2). Photoelectrochemical chlorine production is demonstrated at proof-of-concept scale in 4 M NaCl and suggested to be linked mainly to the production of Ti(III) surface species by vacuum-annealing, as detected by post-catalysis XPS, rather than to Sr/Ba doping at the rutile surface. The vacuum-annealing treatment is proposed to beneficially affect (i) bulk semiconductor TiO2 nanocrystal properties and electron harvesting, (ii) surface TiO2 reactivity towards chloride adsorption and oxidation, and (iii) FTO substrate performance.

Polymers of intrinsic microporosity (PIMs) as molecularly rigid polymers have emerged as a new class of gas‐permeable glassy materials. They offer excellent processability and a range of potential applications also in electrochemical processes. Particularly interesting is the ability of some PIM films to remain gas‐permeable/binding even in the presence of (aqueous) liquid electrolyte to give triphasic interfacial reactivity. Gaseous reagents or products (such as hydrogen or oxygen) are bound probably into hydrophobic regions in the wet PIM film to avoid macroscopic bubble formation and to enhance both the surface reactivity and the apparent activity of the gas solute close to the electrode/catalyst surface. The photoelectrochemical formation of hydrogen gas close to a platinum electrode is enhanced by PIM‐1, which is presented as an example of energy harvesting through molecular H2 “energy carrier” transport.

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The polymer of intrinsic microporosity PIM-1 is employed to disperse and deposit a Pt@titanate nanosheet photocatalyst film. The resulting microporous films allow electrolyte and oxygen permeation to give conventional oxygen reduction voltammetric responses on glassy carbon or on platinum disk electrodes in the dark. Preliminary data are presented showing that with pulsed light from a blue LED (385 nm) oxygen reduction at the electrode is effectively "switched off". A mechanism is tentatively assigned as photocatalytic depletion of oxygen near the electrode. Photoelectrochemical current responses are observed in aqueous NaOH, NaCl, Na 2 HPO 4 and shown to be light intensity and oxygen concentration dependent. Electroanalytical applications are suggested.