Climate change has become a considerable concern for humanity during this anthropocentric era. Scientists believe that the rate of global warming and climate change varies directly with the increase in the concentration of greenhouse gases, particularly carbon dioxide. Urbanization is happening at a higher rate in this era than in any other generation. It was reported that the building sector plays a critical role in the emission of carbon dioxide (CO₂) into the atmosphere. Construction of buildings, operation, and utilization of the built environment has led to emissions of a large number of CO₂ into the ambient air. Various issues and challenges arise from the building sector in reducing CO₂ emissions. The exploitation of non-renewable energy resources, poor building design, and lack of sustainability consideration in urbanization has been holding back CO₂ emission mitigation measures in the building sector. Therefore, CO₂ emission mitigation plans and schemes are necessary alongside standardized frameworks and guidelines. The strategies to reduce CO₂ in the building sector are enforcing standards and policy, conducting impact assessment, adopting low carbon technology, and restricting energy utilization. All stakeholders must play their roles efficiently to reduce CO₂ emissions and aid in the fight against climate change.

Polycyclic aromatic hydrocarbons (PAHs) are a class of naturally occurring chemicals resulting from the insufficient combustion of fossil fuels. Among the PAHs, phenanthrene is one of the most studied compounds in the marine ecosystems. The damaging effects of phenanthrene on the environment are increasing day by day globally. To lessen its effect on the environment, it is essential to remove phenanthrene from the water resources in particular and the environment in general through advanced treatment methods such as photocatalytic degradation with high-performance characteristics and low cost. Therefore, the combination of metals or amalgamation of bimetallic oxides as an efficient photocatalyst demonstrated its propitiousness for the degradation of phenanthrene from aqueous solutions. Here, we reviewed the different nanocomposite materials as a photocatalyst, the mechanism and reactions to the treatment of phenanthrene, as well as the influence of other variables on the rate of phenanthrene degradation.