Globally increasing energy demands and environmental concerns related to the use of fossil fuels have stimulated extensive research to identify new energy systems and economies that are sustainable, clean, low cost, and environmentally benign. Hydrogen generation from solar-driven water splitting is a promising strategy to store solar energy in chemical bonds. The subsequent combustion of hydrogen in fuel cells produces electric energy, and the only exhaust is water. These two reactions compose an ideal process to provide clean and sustainable energy. In such a process, a hydrogen evolution reaction (HER), an oxygen evolution reaction (OER) during water splitting, and an oxygen reduction reaction (ORR) as a fuel cell cathodic reaction are key steps that affect the efficiency of the overall energy conversion. Catalysts play key roles in this process by improving the kinetics of these reactions. Porphyrin-based and corrole-based systems are versatile and can efficiently catalyze the ORR, OER, and HER. Because of the significance of energy-related small molecule activation, this review covers recent progress in hydrogen evolution, oxygen evolution, and oxygen reduction reactions catalyzed by porphyrins and corroles.

Positively-charged gold nanoparticles possess intrinsic peroxidase-like activity, and can catalyze oxidation of the peroxidase substrate 3,3,5,5-tetramethylbenzidine (TMB) by H(2)O(2) to develop a blue color in aqueous solution, thus providing a simple approach to colorimetric detection of H(2)O(2) and glucose.

Artificial photosynthesis provides a blueprint to harvest solar energy to sustain the future energy demands. Solar‐driven water splitting, converting solar energy into hydrogen energy, is the prototype of photosynthesis. Various systems have been designed and evaluated to understand the reaction pathways and/or to meet the requirements of potential applications. In solar‐to‐hydrogen conversion, electrocatalytic hydrogen and oxygen evolution reactions are key research areas that are meaningful both theoretically and practically. To utilize hydrogen energy, fuel cell technology has been extensively investigated because of its high efficiency in releasing chemical energy. In this review, general concepts of the photosynthesis in green plants are discussed, different strategies for the light‐driven water splitting proposed in laboratories are introduced, the progress of electrocatalytic hydrogen and oxygen evolution reactions are reviewed, and finally, the reactions in hydrogen fuel cells are briefly discussed. Overall, the mass and energy circulation in the solar‐hydrogen‐electricity circle are delineated. The authors conclude that attention from scientists and engineers of relevant research areas is still highly needed to eliminate the wide disparity between the aspirations and realities of artificial photosynthesis.