Boosting visible-light driven solar-fuel production over g-C3N4/tetra(4-carboxyphenyl)porphyrin iron(III) chloride hybrid photocatalyst via incorporation with carbon dots

The g-C3N4-C0.05/FeTCPP hybrid photocatalysts exhibit high activity for the solar-fuels production under visible-light irradiation by virtue of the enhanced charge separation and electron transfer due to the incorporation of carbon dots into g-C3N4. [Display omitted] •g-C3N4-Cx has been synthesized through thermal pyrolysis of citric acid and urea.•Appropriate carbon dots incorporation can improve charge separation of g-C3N4.•Carbon dots can promote interfacial electron transfer from g-C3N4 to FeTCPP.•Carbon dots can improve photocatalytic performance of g-C3N4-Cx/FeTCPP.•g-C3N4-C0.05/FeTCPP hybrid photocatalyst exhibits the highest CO and H2 evolution. Developing highly efficient photocatalysts for solar-fuels production under visible-light irradiation is of great promise, but still remains a big challenge. In this work, we use g-C3N4 incorporated with carbon dots as the photosensitizer to couple with tetra(4-carboxyphenyl)porphyrin iron(III) chloride (FeTCPP) molecular catalyst. The obtained g-C3N4-C0.05/FeTCPP hybrid photocatalyst exhibits high activity for the solar-fuels production of CO and H2 under visible-light irradiation, with CO yield of 23.1 mmol/g and H2 yield of 71.1 mmol/g in 6 h. The enhanced mechanism has been studied by various techniques like photocurrent response, photoluminescence and mid-infrared femtosecond transient absorption. The presence of trace amount of carbon dots in the system can provide an alternative channel for the electron transfer, i.e., from g-C3N4 to FeTCPP via the CDs. Accordingly, the interfacial charge separation and electron transfer can be promoted, leading to enhanced photocatalytic performance of the g-C3N4-Cx/FeTCPP hybrid photocatalysts.