To enhance the charge separation efficiency of g-C₃N₄ and facilitate electron transfer between photosensitizer and molecular catalyst, polarization and coordination strategies are used by grafting pyridine rings onto the edge of the g-C₃N₄ framework. Herein, electron-withdrawing pyridine edge-functionalized g-C₃N₄ (g-C₃N₄-P_x) was synthesized via facile one-step thermal polymerization of urea and 4-aminopyridine, and employed as visible-light photosensitizer hybridized with cobalt phthalocyanine (CoPc) for efficient photoreduction of CO₂. Both experimental and theoretical results confirm that electron-withdrawing pyridine grafting facilitates in-plane charge separation and directs electron migration toward the edge of g-C₃N₄, narrows its band gap for enhanced visible-light absorption, and provides dynamic coordination sites that significantly boost interfacial electron transfer from g-C₃N₄-P_x to CoPc. A significant increase in the CO yield was achieved with the optimized CoPc/g-C₃N₄-P_1.5 hybrid, reaching 14.95 mmol g⁻¹ after 6 hours of visible-light irradiation—a 6.1-fold improvement over the unmodified CoPc/g-C₃N₄ (2.47 mmol g⁻¹). This work provides a facile approach for developing highly efficient hybrid photocatalysts for CO₂ reduction and improving the charge separation and visible-light absorption in organic semiconductors.

Polyoxometalate (POM)-based binary and ternary hybrids, including combinations of POMs, semiconductors, nanostructured carbon (carbon nanotubes, graphene, carbon dots, etc.), and metal nanoparticles (MNPs), are key materials in photoelectrocatalysis. POM plays a key role in the construction of nanohybrids and contributes to their photoelectrochemical catalytic properties. These composites combine the properties of two or three functional nanoscale materials, resulting in a wide range of applications, including catalysis, energy conversion and storage, molecular sensors, and electronics. Herein, we summarize the latest progress in POM-based binary nanohybrids (POM/metal, POM/semiconductor, and POM/nanocarbon) and ternary nanohybrids (metal/POM/nanocarbon), particularly in energy materials for photocatalysis, fuel cells, biosensors, and photoelectrochemical devices. Current applications are critically assessed, and promising target systems are discussed.