Renewable energy powered electrocatalytic water splitting is a promising strategy for hydrogen generation, and the design and development of high-efficiency and earth-abundant electrocatalysts for hydrogen evolution reaction (HER) are highly desirable. Herein, MoS₂ nanoflowers decorated two-dimensional carbonitride-based MXene Ti₃CN(OH)_x hybrids have been constructed by etching and post-hydrothermal methods. The electrochemical performance of the as-obtained Ti₃CN(OH)_x@MoS₂ hybrids having a quasi core–shell structure is fascinating: An overpotential of 120 mV and a Tafel slope of 64 mV∙dec⁻¹ can be delivered at a current density of 10 mA∙cm⁻². And after 3,000 cyclic voltammetry cycles, it can be seen that there is no apparent attenuation. Both the experimental results and density functional theory (DFT) calculations indicate that the synergetic effects between Ti₃CN(OH)_x and MoS₂ are responsible for the robust electrochemical HER performance. The electrons of –OH group in Ti₃CN(OH)_x are transferred to MoS₂, making the adsorption energy of the composite for H almost vanish. The metallic Ti₃CN(OH)_x is also beneficial to the fast charge transfer kinetics. The construction of MXene-based hybrids with optimal electronic structure and unique morphology tailored to the applications can be further used in other promising energy storage and conversion devices.

Due to their unique properties and uninterrupted breakthrough in a myriad of clean energy-related applications, carbon-based materials have received great interest. However, the low selectivity and poor conductivity are two primary difficulties of traditional carbon-based materials (zero-dimensional (0D)/one-dimensional (1D)/two-dimensional (2D)), enerating inefficient hydrogen production and impeding the future commercialization of carbon-based materials. To improve hydrogen production, attempts are made to enlarge the surface area of porous three-dimensional (3D) carbon-based materials, achieve uniform interconnected porous channels, and enhance their stability, especially under extreme conditions. In this review, the structural advantages and performance improvements of porous carbon nanotubes (CNTs), g-C₃N₄, covalent organic frameworks (COFs), metal-organic frameworks (MOFs), MXenes, and biomass-derived carbon-based materials are firstly summarized, followed by discussing the mechanisms involved and assessing the performance of the main hydrogen production methods. These include, for example, photo/electrocatalytic hydrogen production, release from methanolysis of sodium borohydride, methane decomposition, and pyrolysis-gasification. The role that the active sites of porous carbon-based materials play in promoting charge transport, and enhancing electrical conductivity and stability, in a hydrogen production process is discussed. The current challenges and future directions are also discussed to provide guidelines for the development of next-generation high-efficiency hydrogen 3D porous carbon-based materials prospected.