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Environmentally friendly municipal solid waste management is the biggest problem facing several developing countries, including Ghana. Heavy metals pollution generated by landfill leachate has become increasingly concerned due to its potential impact on human health. This study assessed the pollution level and sources of heavy metal levels in groundwater, as well as evaluated the human health risk effect. The sampling technique and sample treatment were done based on the Standard Methods for the Examination of Water and Wastewater. The results suggested that the mean concentration of Pb, Fe, Cd, and Cr was above the acceptable limits of the World Health Organization for drinking water except for Zn and Cu. The heavy pollution index indicates contamination, while hazard index values at sites BH 1 and W 4 were greater than one, suggesting adverse health effects. However, the heavy metal pollution index values were less than the critical limit of 100 for drinking water. Multivariate analysis predicted that lithogenic and anthropogenic factors were the possible sources of water pollution of heavy metal in the Oti community. Thus, multivariate statistical techniques could be a beneficial tool for the evaluation of possible sources of heavy metal contamination. The high levels of heavy metals found in the Oti community suggested a considerable pollution of water by leachate percolation from the landfill site. The findings of the study, which can be used in areas under similar environmental conditions, can offer a valuable benchmark for the design of suitable approaches to manage groundwater resources by both local and national policymakers.

Photocatalytic approaches in the visible region show promising potential in photocatalytic water splitting and water treatment to boost water purification efficiency. For this reason, developing cost‐effective and efficient photocatalysts for environmental remediation is a growing need, and semiconductor photocatalysts have now received more interest owing to their excellent activity and stability. Recently, several metal oxides, sulfides, and nitrides‐based semiconductors for water splitting and photodegradation of pollutants have been developed. However, the existing challenges, such as high over potential, wide band gap as well as fast recombination of charge carriers of most of the semiconductors limit their photocatalytic properties. This review summarizes the recent state‐of‐the‐art first‐principles research progress in the design of effective visible‐light‐response semiconductor photocatalysts through several modification processes with a focus on density functional theory (DFT) calculations. Recent developments to the exchange‐correlation effect, such as hybrid functionals, DFT + U as well as methods beyond DFT are also emphasized. Recent discoveries on the origin, fundamentals, and the underlying mechanisms of the interfacial electron transfer, band gap reduction, enhanced optical absorption, and electron–holes separation are presented. Highlights on the challenges and proposed strategies in developing advanced semiconductor photocatalysts for the application in water splitting and degradation of pollutants are proposed.