Construction of Z-scheme g-C3N4/Al:SrTiO3 heterojunction for enhanced VOCs degradation in asphalt through pyroelectric and photocatalytic coupling

The semiconductor photocatalysts are promising in the degradation of volatile organic compounds (VOCs) but limited by its poor light absorption ability and rapid recombination of photogenerated carriers. In this regard, the heterojunction composites composed of graphitic carbon nitride (CN) and Al-doped BaTiO3 (Al:STO) were constructed and its pyro-photocatalytic coupling degradation performance and mechanism of VOCs in asphalt were investigated in this study. The results show that the presence of a temperature difference outside triggers polarization potential on both sides of the pyroelectric Al:STO and induces built-in electric field, which can drive photogenerated electrons and holes to migrate to different polar domains and inhibit their recombination. The constructed CN/Al:STO heterojunctions significantly improve the separation efficiency of photogenerated carriers. The abundant hydroxyl groups generate on the surface of the heterojunction hybrids as reaction intermediate to enhance the degradation rate of VOCs. When the mass ratio of Al:STO to CN is 1:1, the degradation efficiency of VOCs can reach 72.05 % at 50 min. Besides, the temperature sweep test results demonstrate that the addition of this composite material enhances the rutting resistance of asphalt. This study presents the utilization of heterojunction composites as filler in asphalt for enhanced VOCs degradation during mixing and service.