Developing efficient alternatives to the widely used Pt cocatalyst in photocatalytic H₂O splitting is of great importance in view of large-scale production of clear H₂ energy. Herein, we report the facile synthesis of NiCo₂S₄ and its first use as a highly active and cost-affordable cocatalyst to boost visible light H₂ generation with the CdS semiconductor. The synthesized NiCo₂S₄/CdS composite materials are fully characterized by various techniques including X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy-dispersive X-ray (EDX) spectroscopy, X-ray photoelectron spectroscopy (XPS), UV-Vis diffusion reflectance spectroscopy (DRS), and N₂ adsorption measurements. With the optimized NiCo₂S₄/CdS composite sample, a high H₂ generation rate of 137 μmol h⁻¹ is obtained under visible light irradiation, which is more than 17 times higher than that of bare CdS material. The results of photoluminescence (PL) spectroscopy, transient photocurrent response and electrochemical impedance spectroscopy demonstrate the remarkably promoted migration and separation of photogenerated charge carriers over the heterostructured NiCo₂S₄/CdS material, thus leading to obviously enhanced photocatalytic performance. Moreover, a possible mechanism for the photocatalytic H₂ evolution reaction is also proposed based on the observed results of activity evaluation and photoelectrochemical measurements.

中文翻译：

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开发有效的NiCo ₂ S ₄助催化剂，改善CdS纳米粒子的可见光H ₂析出性能

鉴于大规模生产透明的H ₂能量，开发在光催化H ₂ O裂解中广泛使用的Pt助催化剂的有效替代方法非常重要。在本文中，我们报道了NiCo ₂ S _4的合成方法及其首次用作高活性和成本可承受的助催化剂，以提高CdS半导体产生可见光H _2的能力。合成的NiCo ₂ S ₄/ CdS复合材料具有多种技术特征，包括X射线衍射（XRD），扫描电子显微镜（SEM），透射电子显微镜（TEM），能量色散X射线（EDX）光谱，X射线光电子能谱（ XPS），UV-Vis扩散反射光谱（DRS）和N ₂吸附测量。使用优化的NiCo ₂ S ₄ / CdS复合样品，高H ₂生成速率为137μmolh ^-1在可见光照射下获得的汞比裸露的CdS材料高17倍以上。光致发光（PL）光谱，瞬态光电流响应和电化学阻抗谱的结果表明，异质结构NiCo ₂ S ₄ / CdS材料上光生电荷载流子的迁移和分离显着促进，从而显着增强了光催化性能。此外，基于活性评估和光电化学测量的观察结果，还提出了光催化H ₂放出反应的可能机理。