CoFe alloy embedded in N-doped carbon nanotubes derived from triamterene as a highly efficient and durable electrocatalyst beyond commercial Pt/C for oxygen reduction

For development of green and sustainable energy, it is of importance to search highly efficient and low-cost electrocatalysts of oxygen reduction reaction (ORR) in energy conversion devices. Herein, CoFe alloyed nanocrystals embedded in N-doped bamboo-like carbon nanotubes (CoFe@NCNTs) were facilely synthetized by one-step co-pyrolysis with the mixture of triamterene, metal chlorides and graphitic carbon nitride (g-C₃N₄). The resultant CoFe@NCNTs exhibited excellent ORR activity with the positive shifts in the onset potential (E_onset = 0.97 V) and half-wave potential (E_1/2 = 0.88 V), outperforming commercial Pt/C (E_onset = 0.96 V; E_1/2 = 0.84 V). Compared to metal organic frameworks (MOFs)-based strategy for synthesis of low-cost carbon-based ORR catalysts, this method is simple and convenient, coupled by avoiding the complicated synthesis of MOFs and its ligands. This work provides a promising route to fabricate advanced transition-metal-based carbon catalysts in the researches correlated with energy conversion devices.

Graphite carbon nitride doped with a benzene ring for enhanced photocatalytic H2 evolution

Graphitic carbon nitride (g-C₃N₄) has been identified as a promising material for photocatalytic hydrogen (H₂) production, but it shows a low activity. Herein, g-C₃N₄ doped with a benzene ring (B-CN_x) was synthesized via a simple thermal polycondensation method, exhibits 5.4 times higher H₂ evolution rate than the pristine one, and achieves a high apparent quantum yield of 4.11% at 420 nm.

Noble Metal-Free Photocatalysts Consisting of Graphitic Carbon Nitride, Nickel Complex, and Nickel Oxide Nanoparticles for Efficient Hydrogen Generation

A facile and simple synthetic route is developed to prepare earth-abundant and noble metal-free hybrid photocatalysts, which are composed of graphitic carbon nitride (CN), nickel complex, and NiO _x nanoparticles. Bimolecular nucleophilic substitution reaction was employed to attach a nickel complex onto a graphitic CN framework through covalent bonds to support its high loading and dispersion. NiO _x nanoparticles were further incorporated into the catalysts to serve as a hole-transporting medium to improve the separation of photogenerated carriers for higher photocatalytic activity. Both yNiL/CN and yNiL/NiO _x/CN exhibit superb H₂ evolution activity. The optimum H₂ evolution rate of the binary photocatalysts yNiL/CN reaches 303.3 μmol·h^-1·g^-1, whereas that of the ternary photocatalysts yNiL/NiO _x/CN reaches 524.1 μmol·h^-1·g^-1, and the apparent quantum efficiency reaches 1.46% at 450 nm. This finding reveals that coordination of a nickel complex is significant in promoting photocatalytic performance, and the incorporation of NiO _x nanoparticles as a hole-transporting medium is beneficial for separation of the photogenerated charge carriers. The novel hybrid system offers a new horizon for designing transition-metal complex-modified graphitic CN as noble metal-free and highly active photocatalysts for efficient visible light-driven hydrogen generation.

Phenyl-grafted carbon nitride semiconductor for photocatalytic CO2-reduction and rapid degradation of organic dyes

Molecular engineering of graphitic carbon nitride (g-C₃N₄) is achieved by the copolymerization of π-conjugated phenyl urea, melamine, and urea.