Construction of CdS@Cu2-xS core−shell p-n heterojunction with enhanced charge separation for wide spectrum photocatalytic H2 evolution

• CdS@Cu 2-x S core-shell p-n heterostructure was prepared by in situ cation exchange. • Cu 2-x S nanoparticles extended the light response of CdS to NIR region. • The formed CdS@Cu 2-x S p-n heterojunction was certified by the in-situ XPS. • The highest photocatalytic H 2 evolution rate of 8176.5 μmol g − 1 h −1 is achived over CdS@Cu 2-x S-2. Development of wide spectrum photocatalysts have become research hotspot in efficient solar energy-chemical conversion. In this work, a novel CdS@Cu 2-x S core-shell p-n heterojunction was designed by cation exchange method for photocatalytic H 2 evolution. The formation of built-in electric field on CdS@Cu 2-x S core-shell p-n heterojunction effectively accelerates the separation efficiency of photogenerated carriers. The highest photocatalytic hydrogen evolution rate is 8176.5 μmol g − 1 h −1 over optimized CdS@1%Cu 2-x S-2 p-n heterojunction, which is 3.85 times higher than hexagonal CdS. And the highest AQE of 2.60% is acquired at 475 nm. The enhanced photocatalytic activity of the CdS@Cu 2-x S p-n heterojunction is mainly attributed to the effect of the built-in electric field generated by p-n heterojunction, which improves the separation efficiency of photogenerated carriers. More importantly, the formed CdS@Cu 2-x S p-n heterojunction with built-in electric field steering photogenerated carrier separation was certified by in-situ XPS. This work provides effective strategy to construction of p-n heterojunction for wide spectrum photocatalysis. A novel CdS@Cu 2-x S core-shell p-n heterojunction was designed by cation exchange method for wide spectrum photocatalytic H 2 evolution. The enhanced photocatalytic activity of the CdS@Cu 2-x S p-n heterojunction is mainly attributed to the effect of the built-in electric field generated by p-n heterojunction, which improves the separation efficiency of photogenerated carriers. More importantly, the formed CdS@Cu 2-x S p-n heterojunction with built-in electric field steering photogenerated charge separation was certified by the in-situ XPS .