Co-modification of amorphous-Ti(IV) hole cocatalyst and Ni(OH)₂ electron cocatalyst for enhanced photocatalytic H₂-production performance of TiO₂

Highlights: • TiO₂ was simultaneously modified with amorphous Ti(IV) and Ni(OH)₂. • Amorphous Ti(IV) and Ni(OH)₂ traps holes and electrons respectively. • Improved photocurrent response and significant hydrogen evolution were observed. • The photocatalyst was stable during the recycling tests. - Abstract: Highly efficient TiO₂ photocatalysts co-modified by amorphous-Ti(IV) hole cocatalyst and Ni(OH)₂ electron cocatalyst (referred to as Ni(OH)₂-Ti(IV)/TiO₂) were prepared by facile two-step process which was the initial formation of amorphous Ti(IV) on the TiO₂ surface via hydrolysis method and the following formation of Ni(OH)₂ via precipitation reaction. It was found that the Ni(OH)₂-Ti(IV)/TiO₂ showed obviously high hydrogen-production performance. When the amount of Ni(OH)₂ and Ti(IV) was 1 wt% and 0.1 wt%, respectively, the hydrogen-production rate of the resultant Ni(OH)₂-Ti(IV)/TiO₂ reached 7280.04 μmol h⁻¹ g⁻¹, which was significantly higher than that of TiO₂, Ti(IV)/TiO₂ and Ni(OH)₂/TiO₂ by a factor of 215, 63 and 1.8, respectively. Moreover, it was found that Ni(OH)₂-Ti(IV)/TiO₂ photocatalyst preserved a steady and highly efficient H₂-production performance during repeated tests and also exhibited a high transient photocurrent density. The enhanced hydrogen-production performance of Ni(OH)₂-Ti(IV)/TiO₂ can be attributed to the synergistic effect of Ti(IV) hole cocatalyst and Ni(OH)₂ electron cocatalyst to simultaneously accelerate the interfacial transfer of photogenerated holes and electrons. The present surface modification of dual cocatalysts can be regarded as one of the ideal strategies for the preparation of highly efficient hydrogen-production materials in view of their abundance, low cost and facile method.