The low separation efficiency of photogenerated charges and severe photocorrosion seriously impeded the application of CdS in photocatalytic water splitting. Here we report new routes to improve the photocatalytic performance of CdS nanowires (NWs) by decorating with Ag2S nanoparticles, so Ag2S/CdS heterojunction is constructed. The Ag2S/CdS heterojunction exhibited optimal photocatalytic H2 evolution rate of 777.3 μmol h−1 g−1, which is 12.1 times higher than that of pure CdS. The intrinsic characteristics of Ag2S/CdS nanocomposites, such as structure, optical properties, and surface chemical state are systematically studied by experimental characterizations and theoretical calculations. The comprehensive analysis demonstrates that the heterojunction between Ag2S and CdS accelerates photoinduced electrons transfer from CdS to Ag2S, enhancing their ability for water splitting. Meanwhile, the holes on the valence band of CdS react with the sacrificial agents, thus leading to the efficient separation of photogenerated electron–hole pairs. This work offers a simple route to synthesize one-dimensional CdS-based nanocomposites for efficient energy conversion driven by visible light.
Zhao Yanmeng,Zhang Zhongping,Sun Dapeng,Li Guangqiang,Lan Xinzheng,Jiang Yang
We explored a facile routine to synthesize morphology-controlled Ag2S–CdS heterostructures. The heterostructures were achieved by a two-step method where CdS nanorods were prepared in the first step, acting as the substrates inducing successive cation exchange reaction
between Cd2+ and Ag+ ion. The nucleation sites of Ag2S can be readily controlled by varying the feed ratios of Ag+ to Cd2+ ion, thus leading to formation of heterostructures with different morphology where Ag2S particles grow
on the tips of the CdS rods, or at multiple locations across the nanorods. HRTEM analysis showed that Ag2S particles were grown on the varied sites of CdS rods with a coherent, quasi-epitaxial interface having different degrees of lattice mismatch. Photoluminescence results showed
that, compared to bare CdS nanorods, enhanced trap emissions were observed after the growth of Ag2S particles on the rods, which can be attributed to the strained interfaces instead of impurities doping.
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