In recent decades, the use of photocatalysts in the evolution of hydrogen (H2) has received much attention. However, the use of the well-known titanium oxide and another photocatalyst as a base for noble metals is limited due to their major weakness in electron-hole pair separation. The use of cocatalysts can be a good way to overcome this problem and provide better performance for the evolution of hydrogen. In this review, suitable high-efficiency cocatalysts for solar hydrogen production have been thoroughly reviewed. New strategies and solutions were examined in terms of increasing the recombination of charge carriers, designing reactive sites, and enhancing the wavelengths of light absorption. Several new types of cocatalysts based on semiconductors in noble groups and dual metals have been evaluated. It is expected that these photocatalysts will be able to reduce the activation energy of reaction and charge separation. In this regard, the existing views and challenges in the field of photocatalysts are presented. The characteristics of monoatomic photocatalysts are reviewed in this manuscript and the latest advances in this field are summarized. Further, the future trends and upcoming research are also briefly discussed. Finally, this review presents noble metal-based photocatalysts for providing suitable photocatalysts on a larger scale and improving their applicability.

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