Tube wall delamination engineering induces photogenerated carrier separation to achieve photocatalytic performance improvement of tubular g-C3N4

Morphology adjustment is a feasible method to change the physicochemical properties of photocatalysts. The issue that excessively thick tube wall of tubular g-C₃N₄ is not conducive to the electron migration from inside to the surface thus inhibiting the separation of photogenerated carriers has always been ignored. Potassium ions were used to regulate the structure of the tubular supramolecular precursor by breaking hydrogen bonds, thereby promoting the synthesis of delaminated laminar tubular g-C₃N₄ (K-CN), which not only shortened the transfer distance of photogenerated electrons but also provided abundant reaction active sites. Experiments and DFT calculations were combined to reveal the details of the physicochemical properties of K-CN. The photocatalytic capacity of K-CN for tetracycline hydrochloride (TCH) degradation and H₂O₂ generation were 83% and 133 μM, respectively. This work not only synthesized a novel delaminated tubular g-C₃N₄ but also provided a strategy and inspiration for structure and performance optimization for tubular g-C₃N₄.

Neodymium oxide (Nd2O3) coupled tubular g-C3N4, an efficient dual-function catalyst for photocatalytic hydrogen production and NO removal

Graphitic carbon nitride (g-C₃N₄) has emerged as a most promising photocatalyst, non-toxicity and low density, but it is plagued by low activity due to the small specific surface area and poor quantum efficiency. Morphological engineering and coupling with other materials to form hybrids have proven to be effective strategies for enabling high photocatalytic performances. Here, neodymium oxide (Nd₂O₃) coupled tubular g-C₃N₄ composites had been facilely synthesized by a solvent evaporation and high-temperature calcination method to realize efficient photocatalytic activity of hydrogen production and NO removal. A series of characterizations, such as XRD, ESR, in-situ DRIFTS, etc., were used to analyze the physical and chemical properties of the bifunctional photocatalyst, which demonstrated that the composite material had more active sites and a faster electron transfer rate. The optimal sample (1 wt% Nd₂O₃/CN-T) had a H₂ generation rate of 4355.34 μmol·g^-1·h^-1, which was 9.46 times than that of original g-C₃N₄ obtained through heating melamine (CN-M). In addition, the NO removal rate was also 32.32% higher than that of original CN-M. On the basis of the above photocatalytic experimental results and characterizations, a possible mechanism or pathway was proposed and illustrated. This work could provide a feasible strategy to fabricate tubular g-C₃N₄-based composites with rare earth metal oxides (dual-factor regulation) to simultaneously enhance photocatalytic hydrogen production and NO removal efficiently (double application).