Investigation of Photo(electro)catalytic water splitting to evolve H2 on Pt-g-C3N4 nanosheets

Abstract

g-C3N4 has shown great potentials in photocatalytic water splitting to produce hydrogen. Herein, we successfully synthesized g-C3N4 nanosheets via exfoliating bulk g-C3N4. And different metal nanoparticles were photo-deposited onto the surface of g-C3N4 nanosheets. The photocatalytic H2 production activity of g-C3N4 nanosheets increased from 0 to 11.2 μmol/h/gcat. The Pt loaded g-C3N4 nanosheets manifested the highest H2 production activity with a rate of 589.4 μmol/h/gcat. In addition, the hydrogen evolution rate was further enhanced with addition of external bias to fabricate a photoelectrocatalytic (PEC) system. And the maximum hydrogen production rate (23.1 mmol/h/m2) was obtained at a voltage of 0.6 V (vs. Ag/AgCl). The enhancement in H2 production may be due to the following reasons: (1) Two-dimensional atomic flakes is beneficial to increase the specific surface area of g-C3N4, enhance the mobility of carriers, and improve the energy band structure, (2) Pt nanoparticles play an important role in g-C3N4 electron transport, (3) the g-C3N4 nanosheets loaded with Pt nanoparticles exhibited significant enhancement in photoelectrocatalytic performance, which may be attributed to its enhanced electronic conductivity and photoelectrochemical surface area, (4) Pt inhibited the recombination of photogenerated carriers and significantly improved the photocatalytic performance. The enhancement mechanism was deeply discussed and explained in this work.