# Photocatalytic Activity of TiNbC-Modified TiO2 during Hydrogen Evolution and CO2 Reduction
Based on the photocatalytic reaction, H\({}_{2}\) production and CO\({}_{2}\) reduction technology is carried out, which are promising for fuel and energy production because they rely exclusively on natural solar energy to trigger the reaction. In addition, the abundance of available CO\({}_{2}\) and H\({}_{2}\)O acts as a cheap feedstock for photocatalytic reactions. Consequently, CO\({}_{2}\) reduction through solar energy and water splitting is a promising approach to obtaining renewable fuels because of its cheapness and environmental friendliness. Water splitting with release of H\({}_{2}\) and reduction of CO\({}_{2}\) is based on photocatalysts [7; 8; 9; 10; 11; 12; 13; 14; 15; 16; 17; 18; 19; 20; 21] and electrocatalysis [22; 23; 24; 25; 26; 27; 28; 29; 30]. But, the greenest technology for hydrogen production and carbon dioxide reduction is the photocatalytic reaction. Most works on photocatalytic H\({}_{2}\) production and CO\({}_{2}\) reduction are devoted to model MXene Ti\({}_{3}\)C\({}_{2}\)T\({}_{x}\) in combination with various semiconductors: TiO\({}_{2}\), ZnS, CdS, MoS\({}_{2}\), g-C\({}_{3}\)N\({}_{4}\), etc. [7; 8; 9; 10; 11; 12; 13; 14; 15; 16]. Several works are devoted to Nb\({}_{2}\)C [17; 18]. It was found that a Nb\({}_{2}\)C sample obtained by chemical etching and 4 h ultrasound treatment (Nb\({}_{2}\)C-4h), with a high specific surface area in an aqueous suspension of 161 m\({}^{2}\), measured by methylene blue, showed the highest rate of hydrogen formation of 290 umol/h*g, which was 2-3 times higher than that of Nb\({}_{2}\)C obtained by chemical etching without post-synthetic ultrasound treatment, which has a 55 m\({}^{2}\) specific surface in suspension. An important property of 2D Zr\({}_{2}\)CO\({}_{2}\) and Hf\({}_{2}\)CO\({}_{2}\) is that they have unexpectedly high and directionally anisotropic carrier mobilities, which can effectively promote the migrations and separations of photogenerated electron-hole pairs [19]. In [20], it was shown that the rich chemical composition of transition metal dichalcogenides (TMD), combined with numerous strategies to tune their electronic properties, make these materials very attractive for understanding the fundamental principles of electro- and photocatalysis and for developing highly efficient, renewable, and affordable catalysts for large-scale H\({}_{2}\) production [20]. Recently, scientists around the world have been intensively searching for new photocatalysts operating in the visible range of the spectrum because such photocatalysts activate photocatalytic processes for splitting water with the release of hydrogen, as well as the reduction of carbon dioxide. These processes are related to green energy and are promising research areas for mankind due to the new vector in the energy industry--environmental preservation and the increasing use of renewable energy sources. Dozens of well-established photocatalyst semiconductors are already known. Solar energy can be directly turned to thermal energy by the photothermal effect or converted to fuel and stored for later exploitation. Also, sun irradiation can be used directly for the purpose of water depollution. Historically, titanium dioxide (TiO\({}_{2}\)) and zinc oxide (ZnO) are the materials that really sparked worldwide interest in oxide semiconductors for the above applications. Their main advantages, compared to other types of semiconducting materials, is that they are plentiful in nature and considered environmentally benign. Furthermore, TiO\({}_{2}\) has many useful properties, such as ease of process ability, chemical stability, high surface area, low cost, non-toxicity, and excellent charge migration qualities. Years of research progress have actually allowed the theoretical thermodynamics limits to be approached in aforementioned applications. However, use of solar energy is still not widespread. Semiconductors have wide bandgaps, and they are active only in the UV region.