Photocatalytic reaction and photocatalyst

2 Photocatalysis for ammonia synthesis 10.2.2.1 Photocatalytic reaction and photocatalyst 

Until now, there are many references relevant to electron- and energy-transfer processes occurring in photocatalysis. Many books and reviews can be referred. Here, we only emphasis on the unusual property of photocatalysis processes different from common catalysis processes whether heterogeneous system or homogeneous system. 

There are various interactions between photos and materials. Photocatalysis reaction is one of them. The catalytic reaction and photochemical reaction can be 

In catalytic reaction (10.3), the catalyst (K) is defined as the materials that can enhance reaction rate but does not change equilibrium of reaction at definite temperature. Prom the thermodynamic point of view, the difference in free energy between the initial and final states of reaction (10.3) at constant temperature and 

If all adsorbed photoenergy is used for reaction, the change (AfG ) of free energy in photo-reaction (10.4) will increase. However, the AfG in reaction (10.4) will drop and appear as status of AfG = 0 if the photoenergy adsorbed by the reaction system is transferred to heat energy and is released. 

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