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Self-healing is the way by which nature repairs damage and prolongs the life of bio entities. A variety of practical applications require self-healing materials in general and self-healing polymers in particular. Different (complex) methods provide the rebonding of broken bonds, suppressing crack, or local damage propagation. Here, a simple, versatile, and cost-effective methodology is reported for initiating healing in bulk polymers and self-healing and anticorrosion properties in polymer coatings: introduction of carbon dots (CDs), 5 nm sized carbon nanocrystallites, into the polymer matrix forming a composite. The CDs are blended into polymethacrylate, polyurethane, and other common polymers. The healing/self-healing process is initiated by interfacial bonding (covalent, hydrogen, and van der Waals bonding) between the CDs and the polymer matrix and can be optimized by modifying the functional groups which terminate the CDs. The healing properties of the bulk polymer-CD composites are evaluated by comparing the tensile strength of pristine (bulk and coatings) composites to those of fractured composites that are healed and by following the self-healing of scratches intentionally introduced to polymer-CD composite coatings. The composite coatings not only possess self-healing properties but also have superior anticorrosion properties compared to those of the pure polymer coatings.

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Hydrogen production from water splitting using photocatalysts and solar energy is an ideal pathway to obtain future energy sources which are cheap and easy to industrialize. In the water splitting process, the reduction of H2O gives H2, while H2O oxidation produces O2 with hydrogen peroxide (H2O2) in tiny amounts as a by‐product (poisoning the catalyst). It remains challenging to simultaneously produce H2O2 and H2 within one photocatalytic system. Inspired by a biological H2O2 generator, chlorella, the authors firstly realize the simultaneous photocatalytic water splitting and biological H2O2 generation by a living Chlorella vulgaris and carbon micro particle (needle coke) comodified g‐C3N4 (C‐N‐g‐C3N4) photocatalyst. The C‐N‐g‐C3N4 exhibits the optimal H2O2 (H2) evolution rate of 0.98 µmol h−1 (0.84 µmol h−1), giving an apparent quantum efficiency of 0.86% for H2 evolution at 420 nm. In this system, the needle coke serves as cocatalyst to work as reduction sites for H2 evolution, while the living C. vulgaris plays the key role in the production of H2O2 under the protection of g‐C3N4.