Enzhou Liu,Chenyang Jin,Chenhui Xu,Jun Fan,Xiaoyun Hu
Transition metal phosphides are considered as the most prospective replacements for noble metal cocatalysts used for H 2 evolution during photocatalytic water splitting. In this work, Ni 2 P/g-C 3 N 4 composite photocatalyst was synthesized using a simple in-situ hydrothermal method by one step. Benefiting from the excellent light trapping, efficient transfer of charge carriers and strong stability of Ni 2 P nanoparticles , as well as the stable interface contact between Ni 2 P and g-C 3 N 4 , the Ni 2 P/g-C 3 N 4 exhibit greatly enhanced H 2 evolution performance during photocatalytic water splitting . The optimized H 2 evolution rate can reach 3344 μmol h −1 g −1 over 17.5 wt% Ni 2 P/g-C 3 N 4 , which is 68.2 times greater than that of pure g-C 3 N 4 and even much greater than that of 15 wt% Pt/g-C 3 N 4 . The apparent quantum efficiency (QE) is about 9.1% under 420 nm monochromatic. The enhancement mechanism was demonstrated in detail by transient photocurrent responses, photoluminescence spectra and electrochemical impedance spectroscopy . This work develops a facile strategy to fabricate transition metal phosphide/semiconductor heterojunction systems with potential application for photocatalytic H 2 evolution.
Shen Xu,Jianying Huang,Zengxing Li,Yonggang Lei,Yingzhen Zhang,Kim Hoong Ng,Yuekun Lai
It is very attractive to find a cheap and efficient cocatalyst for enhancing the H 2 generation of graphitic carbon nitride (CN) under visible light. To achieve that, we proposed a novel two-step method to deposit sub-10 nm metallic Ni 2 P particles on the surface of CN sheets for a maximized interfacial contact. Characteristic results confirmed the establishment of ohmic heterojunction upon Ni 2 P-modification of CN, which deemed to be an effective measure to alleviate photo-charges recombination. In addition to facilitating spatial separation of charges, Ni 2 P could also enhance the optical properties of CN while reducing its impedance for interfacial electron shuttling. Better still, the P-end of Ni 2 P is highly electronegative, offering desirable H + -capturing capability for enhanced H 2 generation. These give rise to an improved H 2 production of Ni 2 P/CN composite, optimally at 645.3 μmol g −1 ·h −1 as compared to immeasurable H 2 yielded by the pristine CN. Such photocatalytic performance is even comparable to the Pt-modified CN photocatalyst (640.6 μmol g −1 ·h −1 ). In recyclability test, a notable activity suppression of 33.17% was recorded after four reaction cycles. This can be ascribed to the pronounced photo-corrosion of the Ni 2 P cocatalyst during photoreaction. Nonetheless, a remarkably high H 2 generation (1328.6 μmol g −1 in 3 h) was still attained at 4 th cycle. This justifies the effectiveness of our synthesized Ni 2 P cocatalyst in enhancing H 2 generation of CN under visible light irradiation.
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