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Hydrogen is a promising alternative energy without greenhouse gas emissions. The transition metal carbides (TMCs) are considered a sustainable alternatives to noble metals in catalysis. Among the TMCs, Co${}_x$C ($x$ = 2, 3) nanoparticles (NPs) act as an excellent electrocatalyst for hydrogen evolution reaction (HER) by water splitting. In our report, Co${}_x$C nanocomposites were synthesized by wet chemistry method using cobalt (II) acetate, sodium hydroxide as precursors and triethylene glycol as solvent. In addition, Co₂C NPs were synthesized by similar wet chemistry method using cobalt (II) acetate as precursors and triethylene glycol, oleylamine as solvent. The cobalt carbide NPs exhibited high electrocatalytic activity. Co${}_x$C nanocomposites performed a −0.33 V onset potential and 91 mV/dec Tafel slope, while the Co₂C NPs exhibited a better performance of −0.27 V and 60 mV/dec, respectively.

In molybdenum disulfide (MoS₂), cobalt (Co) doping is an effective way to introduce catalytic active sites on the basal plane. For improving their capability of electrocatalytic hydrogen evolution reaction (HER), it is desirable to produce more active sites and endow them with highly electrocatalytic activity. In this work, we used silicon dioxide (SiO₂) nanospheres as template to prepare porous Co-doped MoS₂ with different Co content. We found that the prepared porous catalyst has improved the catalytic performance. Furthermore, the increase in Co content not only increases the number of active sites, but also can improve the activity for each Co atom. First-principle calculations based on density functional theory (DFT) suggest that this mutually enhanced activity originates from the shift of the density of state (DOS) of the vertical d${}_{z2}$ orbital near the Fermi energy level caused by the interaction among the Co atoms.

Hydrogen energy has an advantage over conventional fossil energy because of its clean and low-carbon features, while its stability gives it an advantage over renewable energy sources such as hydropower, photovoltaic (PV) power, and wind power. Using hydrogen as a fuel can achieve zero carbon emissions or even net zero emissions at the end of energy conversion. Moreover, with hydrogen as the carrier, an energy system of multi-energy complementarity will be established by coupling multiple energy systems such as power grids, gas grids and heat networks, which can realize the comprehensive utilization of renewable energy sources in an efficient, stable, and flexible manner. Based on the “dual carbon” goals, this paper targets sectors with high carbon emissions represented by electric power, steel and transportation, analyzes the feasible path of using hydrogen energy to promote deep carbon reduction, and points out the obstacles faced by hydrogen energy development in various sectors. On account of the current development and expected prospects, this paper proposes that the current focus of hydrogen energy industry is to coordinate the development of industrial sectors and regions, build a pattern that can facilitate the industry’s systematic and concerted development, address key technical challenges (such as green hydrogen production or hydrogen storage and transportation via pipeline), improve industrial standards, and promote the industry’s development in a balanced, coordinated and orderly way.

Hydrogen energy is a clean and efficient secondary energy source, and hydrogen derived from renewable sources is regarded as the key to achieving a low-carbon clean energy supply. Currently, the hydrogen energy supply chain is still in its development stage and requires a comprehensive comparative analysis of various hydrogen production technologies as well as storage and transportation methods to ensure the optimal application route for hydrogen energy. In this study, GaBi 10 software is used to conduct a comparative and evaluative analysis of the potential environmental impact associated with hydrogen energy application. The life cycle assessment encompasses all stages of the hydrogen supply chain, including production, transportation and utilization. The results indicate that hydrogen production from wind power has the lowest global warming potential (GWP), acidification potential (AP), eutrophication potential (EP) and photochemical ozone creation potential (POCP). Due to the high energy consumption of the liquefaction process, liquid hydrogen transportation is currently associated with the largest carbon emissions among all modes of hydrogen transport. However, if renewable energy sources are utilized to power hydrogen liquefaction, significant reductions in carbon emissions can be achieved. An evaluation of the carbon footprint associated with the completed hydrogen supply chain indicates that hydrogen produced from renewable sources is cost-effective for use in gas-fired boilers from an environmental perspective.