## 1 Introduction  
The world is facing an energy crises nowadays. A rough estimation shows that, in 2050, the energy consumption will be doubled when compared to 2020 [1]. Now, the world is dependent on nonrenewable energy sources to meet energy requirements [2]. However, with the increase in energy prices, energy demand, and global warming, researchers are thinking about renewable energy resources [3, 4]. The main reasons for the increase in energy demand are the world's high growth rate and a great industrial revolution. Throughout the whole history of humankind, humans used energy from fossil fuels. In the past, only two types of fossils (wood and charcoal) were used, but, due to the industrial revolution, many more options, including oil, coal, and natural gas [5, 6], have also been used to meet the energy requirements. According to a survey, fossil fuel reservoirs have been enough for decades, but, with time, these reservoirs are depleting [7, 8]. Modern day research is focused on developing renewable energy sources, and water splitting is a promising source of energy [9, 10]. There has been a noticeable increase in oxygen evolution reaction (OER) in recent years, and it is estimated that this increase will be doubled in future years [11, 12]. The conventional method of hydrogen and oxygen output involves a steam reforming method [13]. Nowadays, O\({}_{2}\) is also produced by using the photocatalytic method. In these methods, sunlight is used to create oxygen and hydrogen molecules. Solar water splitting methods of oxygen and hydrogen production include thermochemical and photobiological methods [14; 15]. In the water-splitting process, sunlight is used as an energy source, and a water molecule is used as an electron donor to complete fuel cells [16]. Two half reactions are involved: the first one is the hydrogen evolution reaction, and the second one is the oxygen evolution reaction. Different types of charge separators are used to enhance the rate of reaction. Some of the charge separators are semiconductors, such as nanobelts, nanotubes, nanowires, and nanosheets [17; 18]. Hetrojunction semiconductors are also being used for better charge separation. Cobalt is commonly used as a catalyst in hydrogen and oxygen evolution reactions [19]. Photolytic corrosion is the main problem in these reactions. This problem can be minimized by increasing electrodes' stability and providing more active sites for the photocatalytic activity of hydrogen and oxygen [20]. Researchers are exploring other options, such as nitrides, phosphides, selenides, and carbides [21; 22]. These types of non-nobel metal catalysts show high corrosion resistance and better electroconductivity [23; 24; 25; 26; 27; 28]. Some highly efficient catalysts recently reported for HER are CoS\({}_{2}\), FeS\({}_{2}\), MoSe\({}_{2}\), g-C\({}_{3}\)N\({}_{4}\)/Co-MOF (ZIF-67), g-C\({}_{3}\)N\({}_{4}\)/Nb\({}_{2}\)O\({}_{5}\), CdS QD/MoO\({}_{3}\)-OV/g-C\({}_{3}\)N\({}_{4}\), and NiS\({}_{2}\)[1; 2; 3; 4]. Nanotubes and nanosheets are used to increase active sites for electrocatalytic HER nanowires [28; 29]. Metal carbides show similar behavior, in terms of catalytic properties and electronic band. Due to these reasons, carbides show high hydrogen adsorption and maximum electrical conductivity [30]. Due to the presence of a d-band structure, they show high electrical conductivity and low hydrogen adsorption capacity. Mo\({}_{2}\)C and WC are both categorized as non-Pt catalysts for hydrogen evolution reactions. These have been tested at different pH ranges and proved to be a stable support for HER [31]. Some catalysts can perform both oxygen and hydrogen evolution reactions [32; 33]. Pt, Rh, and Ir-based catalysts can serve as bifunctional catalysts, but such types of catalysts are lower in number and have very high costs [34]. The great challenge in this field is to find a low cost, easily available bifunctional catalyst that can work both in acidic and basic environments [35; 36].