Molybdenum‐Based Co‐catalysts in Photocatalytic Hydrogen Production: Categories, Structures, and Roles

Abstract

Photocatalytic hydrogen production by using solar energy has attracted great interest around the world. The main challenges are the high costs of the photocatalysts and the low efficiency of photocatalytic hydrogen production. Co-catalysts, as crucial components of photocatalysts, are usually used to stimulate photoexcited electron transfer from the light absorber to the surface, and they also catalyze the proton-reduction reaction to form H in water. However, most co-catalysts used in photocatalytic hydrogen production are noble metals, which are expensive and contradict the low-costs demanded by industry. Therefore, the development of earth-abundant and cheap co-catalysts to replace noble metals is necessary for photocatalytic H production. This account highlights the performance and roles of molybdenum-based non-noble metal co-catalysts in photocatalytic hydrogen production. We developed a series of inexpensive and efficient molybdenum-based co-catalysts. We demonstrated that more H could be produced by loading Mo-based co-catalysts on CdS by using the co-precipitation method than by using traditional Pt/CdS same under the same photocatalytic conditions. The molybdenum-based co-catalysts were able to form heterojunctions, which served as bridges to facilitate the transport and separation of photogenerated charges; moreover, the molybdenum-based co-catalysts were able to accept and store photoexcited electrons owing to their large specific capacitance. The stored photoelectrons could then be released according to proton-reduction processes to form H . Furthermore, the molybdenum-based co-catalysts were found to have metastable state structures and multiple valence states, which provided more active sites and effectively catalyzed the production of H and inhibited the reverse reaction. The discovery of Mo-based co-catalysts with superior properties will provide guidance for the design of new co-catalysts.

WXy/g‐C3N4 (WXy=W2C, WS2, or W2N) Composites for Highly Efficient Photocatalytic Water Splitting

“…[1][2][3] Sustainable hydrogen production through renewable energy sources, such as solar,w ind and hydroelectric energies, is an attractive method. [11][12][13][14][15] Traditionally,n oble metalsw ith excellent HER activity are efficient cocatalysts for the photocatalytic reaction, especially the most popularP t, but their large-scale application are limited by high costs and scarcity. [4][5][6][7][8][9][10] Although numerous studies on photocatalytic hydrogen production have been performed,f urther investigation is still neededt oo btain highly activea nd stable photocatalysts and to understand the photocatalytic mechanism.…”

“…The decoration of the surface with as uitable cocatalyst that has ah igh HER (hydrogen evolution reaction) activity could not only significantly boost the surfaceh ydrogen evolution but also improve the efficiencyo fc arriers eparation and transfer. [11][12][13][14][15] Traditionally,n oble metalsw ith excellent HER activity are efficient cocatalysts for the photocatalytic reaction, especially the most popularP t, but their large-scale application are limited by high costs and scarcity. [16][17][18][19] Therefore, the use of earth-abundant, cheap and HER-activec ocatalysts is one of the keys to the practical application of photocatalytic hydrogen production.…”

A Novel Earth‐Abundant W‐WC Heterojunction as Efficient Co‐Catalyst for Enhanced Photocatalytic H2Evolution

“…[33][34][35] Our group is committed to non-noble metal co-catalysts and reported a series of molybdenum-based co-catalysts (MoP, Mo 2 N, Mo 2 C, Mo 2 C/Mo 2 N/GR, Pt/ Mo 2 N, RodÀ Mo 2 N). [36][37][38][39][40][41][42] And the most of important, we clarified the different roles of noble metal and non-noble metal cocatalyst. [41,42] The noble metal mainly provides active sites and non-noble metal material mainly acts as reservoir storing electrons, and it is interesting the ultralow amount of noble metal on non-noble metal material leads to the great enhancement of co-catalytic efficiency.…”

In situ one-pot fabrication of MoO3−x clusters modified polymer carbon nitride for enhanced photocatalytic hydrogen evolution

“…Recently, transition metal molybdenum and its derivative compounds (MoS 2 [12], MoN [13], MoC [14]) emerged as promising noble-metal-free cocatalysts for their merits in earth abundant and excellent performance [15]. However, few reports were found to utilize MoO 3−x clusters as cocatalysts in photocatalysis.…”