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Hydrogen energy is environmental-friendly and considered an attractive alternative to fossil fuels. Among the feasible technologies for hydrogen generation, photocatalysis-derived hydrogen from water splitting is considered to be the optimal solution for meeting long-term sustainability and increased energy demands. In this context, various photocatalytic genres are proposed, with metal and carbon-supported photocatalysts demonstrating greater comprehensiveness and potential for addressing solar-driven hydrogen production from water. Several important aspects of the aforementioned photocatalytic genres are reviewed in the present work in an effort to provide pertinent researchers with new horizons for more advanced performance. The review is initiated by introducing the primary principles in photocatalysis, as well as the prerequisites for hydrogen generation from water. The focus then moves to metal-based photocatalysts, where the important features of these materials as photocatalysts are summarized. Related limitations are also discussed, along with the proposed strategies that could potentially mitigate them. Similar systematic summaries are made of knowledge on carbon-based photocatalysts. The review concludes with a discussion of potential future research directions in light of the bottlenecks currently encountered. With the proper research and development, metal-based and carbon-based photocatalysts could produce clean hydrogen from water, thereby fueling global development without causing environmental harm.

A numerical simulation of the performance of a fin‐tube‐type adsorption bed with silica gel/water working pairs was conducted. Three models of the heat recovery cycle, the mass recovery cycle, and a combined heat and mass recovery cycle were closely examined. The main goals were to determine 1) the conditions under which these advanced cycles were most effective and 2) the optimum recovery time. Mass recovery enhanced both the coefficient of performance (COP) and specific cooling power (SCP) by up to 24 and 37.5 %, respectively, at 60 °C, and the enhancements of the COP and SCP were 5.0 and 16.0 %, respectively, at 90 °C. Heat recovery increased the COP by 12.56 %, but reduced the SCP by 10.84 % at 60 °C, whereas, at 90 °C, the COP increased by 11.83 % and SCP decreased by 5.96 %. The mass recovery is more influential at a low heating temperature than that at a high heating temperature. Therefore, in the combined heat and mass recovery cycles, the main contribution to the enhancement of the COP comes from mass recovery at lower water temperature. However, at a high heating temperature, the COP increases mainly due to heat recovery.

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