Hydrogen peroxide is a very important oxidizer used in various fields, which is why it is produced in more than four million tons per year. Currently, most of it is produced using the anthraquinone process, which significantly pollutes the environment due to its high energy consumption and use of organic solvents. Due to this, more attention is being paid to researching new, environmentally friendly production methods. Production with photocatalysis is one of the approaches where the energy source is sunlight. Radiation causes an excited state of the semiconductor or molecule, resulting in charge separation. Then, redox reactions occur on the surface of the catalyst. Its selection is very important, as he must favour the ORR or WOR reaction pathways, where the final product is H$_2$O$_2$. Among the more promising catalysts are TiO$_2$, gC$_3$N$_4$, and catalysts from the COF, MOF, and metal-free polymer groups. The following approach, which is currently the most extensively researched, is electrocatalysis. The electrolytic cell consists of a voltage source, electrolyte, and anode, where oxidation occurs, and cathode, where reduction occurs. Catalysts are in most cases already a part of the electrode, and their purpose is to favour 2e$^−$-ORR and 2e$^−$-WOR, which are the best pathways for H$_2$O$_2$ synthesis. There are many ways to prepare an appropriate catalyst, such as doping, defect engineering, facet engineering, and interface engineering. In addition to metal oxides, which have shown good efficiency, carbon-based catalysts are becoming increasingly popular, as they are more affordable than noble metals. Photoelectrochemical approach combines the properties of photocatalysis and electrocatalysis. The system can consist of a photoanode or a dark anode and a photocathode or a dark cathode, where the photocell reduces the bias and thus reduces the power consumption during the process. Unlike photocatalysis, which in most cases requires sacrificial reagents for effective operation, and electrocatalysis, which contains electrolytes, plasma technology requires only oxygen, water, and a catalyst. A gas-liquid-solid system with plasma discharge initiation with oxygen bubbles in water surrounded by a suspension of solid catalyst is used to produce H$_2$O$_2$. Plasma technology has shown better results than photocatalysis and electrocatalysis, but it requires much more electricity than other approaches.
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