Covalent organic frameworks (COFs) are an emerging type of crystalline and porous photocatalysts for hydrogen evolution, however, the overall water splitting activity of COFs is rarely known. In this work, we firstly realized overall water splitting activity of β-ketoamine COFs by systematically engineering N-sites, architecture, and morphology. By in situ incorporating sub-nanometer platinum (Pt) nanoparticles co-catalyst into the pores of COFs nanosheets, both Pt@TpBpy-NS and Pt@TpBpy-2-NS show visible-light-driven overall water splitting activity, with the optimal H₂ and O₂ evolution activities of 9.9 and 4.8 μmol in 5 h for Pt@TpBpy-NS, respectively, and a maximum solar-to-hydrogen efficiency of 0.23%. The crucial factors affecting the activity including N-sites position, nano morphology, and co-catalyst distribution were systematically explored. Further mechanism investigation reveals the tiny diversity of N sites in COFs that induces great differences in electron transfer as well as reaction potential barriers.

Realization of solar‐driven aerobic organic transformation under atmospheric pressure raises the great challenge for efficiently activating O₂ by tailored photocatalysts. Guided by theoretical calculation, phosphate groups are used to induce the construction of ultrathin Co phthalocyanine/g‐C₃N₄ heterojunctions (CoPc/P‐CN, ≈4 nm) via strengthened H‐bonding interfacial connection, achieving an unprecedented 14‐time photoactivity improvement for UV–vis aerobic 2,4‐dichlorophenol degradation compared to bulk CN by promoted activation of O₂. It is validated that more ^•O₂⁻ radicals are produced through the improved photoreduction of O₂ by accelerated photoelectron transfer from CN to the ligand of CoPc and then to the abundant single Co–N₄ (II) catalytic sites, as endowed by the matched dimension, intimate interface even at the molecular level, and high CoPc dispersion of resulted heterojunctions. Interestingly, CoPc/P‐CN also exhibits outstanding photoactivities in the aerobic oxidation of aromatic alcohols. This work showcases a feasible route to realize efficient photocatalytic O₂ activation by exploiting the potential of ultrathin metal phthalocyanine (MPc) assemblies with abundant single‐atom sites. More importantly, a universal facile strategy of H‐bonding‐dominating construction of MPc‐involved heterojunctions is successfully established.

Highly active and earth-abundant catalysts for hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) play vital roles in developing efficient water splitting to produce hydrogen fuels. Here, we reported an effective strategy to fabricate a completely new nitrogen-doped MoS₂/COF-C₄N vertical heterojunction (N-MoS₂/COF-C₄N) as precious-metal-free bifunctional electrocatalysts for both HER and OER. Compared with MoS₂ and COF-C₄N, the obtained vertical N-MoS₂/COF-C₄N catalyst showed enhanced HER with a low overpotential of 106 mV at 10 mA cm⁻², which is six times lower than MoS₂. The superior acidic HER activity, molecular mechanism, and charge transfer characteristic of this vertical N-MoS₂/COF-C₄N were investigated experimentally and theoretically in detail. Its basic OER activity is almost equal to that of COF-C₄N with an overpotential of 349 mV at 10 mA cm⁻², which showed that the in-situ growing method maintains the exposure of the C active sites to the greatest extent. The preparation and investigation for vertical N-MoS₂/COF-C₄N provide ideas and a research basis for us to further explore promising overall water-splitting electrocatalysts.

The wide-spectrum NiPc–FePc/BCN Z-scheme heterojunctions have been successfully constructed with exceptional photoactivity depending on the cascade Z-scheme electron transfer from BCN to NiPc–FePc, and the synergy of NiPc and FePc promote O₂ reduction.