三维g-C3N4/NixP复合光催化剂的制备及其可见光下产氢性能的研究

以三聚氰胺和三聚氰酸为原料，以水为溶剂采用超分子自组装法制备三维互联框架形貌的3D g-C₃N₄（DCN）。以次磷酸钠和硫酸镍作为磷源和镍源，采用原位光沉积法在3D g-C₃N₄上沉积Ni_xP，制备了3D g-C₃N₄/Ni_xP复合光催化剂。采用扫描电子显微镜（SEM）、透射电子显微镜（TEM）、X射线衍射（XRD）、傅里叶变换红外光谱（FT-IR）、X射线光电子能谱（XPS）、紫外可见漫反射光谱（UV-Vis DRS）等手段对样品进行了表征，结果表明，3D g-C₃N₄/Ni_xP复合光催化剂上均匀负载着直径几十纳米的Ni_xP颗粒并且Ni_xP表现为无定形结构；与体相g-C₃N₄（BCN）和3D g-C₃N₄相比，复合光催化剂有着更好的可见光吸收能力。以三乙醇胺为牺牲剂，在波长λ≥420 nm的可见光下进行产氢试验，研究了3D g-C₃N₄/Ni_xP复合光催化剂的光催化性能。结果表明，光沉积20 min得到的3D g-C₃N₄/Ni_xP复合光催化剂的光催化产氢速率可达1 720 μmol/（g·h），远远大于纯DCN（7 μmol/（g·h））和光沉积20 min得到的BCN/Ni_xP复合光催化剂（15 μmol/（g·h）），并且在经历5个光催化循环产氢测试后其循环性能没有明显降低。

Preparation of a three-dimensional g-C3N4/NixP composite photocatalyst and its hydrogen production performance under visible light irradiation

A supramolecular self-assembly method has been used to prepare 3D g-C₃N₄ (DCN) with a three-dimensional interconnected framework morphology with melamine and cyanuric acid as raw materials and water as solvent. The 3D g-C₃N₄/Ni_xP composite photocatalyst was obtained by in situ photodeposition of Ni_xP on 3D g-C₃N₄ using NaH₂PO₂ and NiSO₄ as the phosphorus and nickel source, respectively. The 3D g-C₃N₄/Ni_xP was characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), X-ray photoelectron spectroscopy (XPS), and ultraviolet-visible diffuse reflectance spectroscopy (UV-Vis DRS). The results showed that the 3D g-C₃N₄/Ni_xP composite photocatalyst is uniformly loaded with Ni_xP particles with a diameter of tens of nanometers, and that the Ni_xP is amorphous. The composite photocatalyst had better visible light absorption capacity than bulk g-C₃N₄ (BCN) or 3D g-C₃N₄. With triethanolamine as a sacrificial agent, hydrogen production was performed under visible light irradiation with wavelength λ≥420 nm, and the photocatalytic performance of 3D g-C₃N₄/Ni_xP composite photocatalyst was studied. The results showed that the photocatalytic hydrogen production rate of the 3D g-C₃N₄/Ni_xP composite photocatalyst when the photodeposition time was 20 min reached 1 720 μmol/(g·h), which is far greater than the corresponding rates for pure DCN (7 μmol/(g·h)) and BCN/Ni_xP (15 μmol/(g·h)). After undergoing five photocatalytic cycle hydrogen production tests, the cycle performance did not significantly decrease.