Recent progress of mesoscience in design of electrocatalytic materials for hydrogen energy conversion

Electrocatalytic materials with different morphologies,sizes,and components show different catalytic behavior in various heterogeneous catalytic reactions.It has been proved that the catalytic properties of these materials are strongly influenced by several factors at different levels,including the electrode morphology,reaction channels,three-phase interface,and surface active sites.Recent developments of mesoscience allow one to study the relationship between the apparent catalytic performance of electro-catalytic materials with these factors from different levels.In this review,following a brief introduction of new mesoscience,we summarize the effect of mesoscience on electrocatalytic material design,including modulating the geometric and electronic structures of materials focusing on morphology(particulate,fiber,film,array,monolith,and superlattice),pore structure(microporous,mesoporous,and hierarchical),size(single atoms,nanoclusters,and nanoparticles),multiple components(alloys,heterostructures,and multiple ligands),and crystal structures(crystalline,amorphous,and multiple crystal phases).By evaluating the electrocatalytic performance of catalytic materials tuned at the mesoscale,we paint a picture of how these factors at different levels affect the final system performance and then provide a new direction to better understand and design catalytic materials from the viewpoint of mesoscience.

Ionic liquids for CO_(2) electrochemical reduction

Electrochemical reduction of CO_(2) is a novel research field towards a CO_(2)-neutral global economy and combating fast accelerating and disastrous climate changes while finding new solutions to store renewable energy in value-added chemicals and fuels.Ionic liquids(ILs),as medium and catalysts(or supporting part of catalysts)have been given wide attention in the electrochemical CO_(2) reduction reaction(CO_(2) RR)due to their unique advantages in lowering overpotential and improving the product selectivity,as well as their designable and tunable properties.In this review,we have summarized the recent progress of CO_(2) electro-reduction in IL-based electrolytes to produce higher-value chemicals.We then have highlighted the unique enhancing effect of ILs on CO_(2) RR as templates,precursors,and surface functional moieties of electrocatalytic materials.Finally,computational chemistry tools utilized to understand how the ILs facilitate the CO_(2) RR or to propose the reaction mechanisms,generated intermediates and products have been discussed.

Optimizing the electronic spin state and delocalized electron of NiCo_(2)(OH)_(x)/MXene composite by interface engineering and plasma boosting oxygen evolution reaction

The electrocatalytic activity of transition-metal-based compounds is closely related to the electronic configuration.However,optimizing the surface electron spin state of catalysts remains a challenge.Here,we developed a spin-state and delocalized electron regulation method to optimize oxygen evolution reaction(OER)performance by in-situ growth of NiCo_(2)(OH)_(x) using Oswald ripening and coordinating etching process on MXene and plasma treatment.X-ray absorption spectroscopy,magnetic tests and electron paramagnetic resonance reveal that the coupling of NiCo_(2)(OH)_(x) and MXene can induce remarkable spin-state transition of Co^(3+)and transition metal ions electron delocalization,plasma treatment further optimizes the 3 d orbital structure and delocalized electron density.The unique Jahn-Teller phenomenon can be brought by the intermediate spin state(t2 _(g)^(5) e_(g)^(1))of Co^(3+),which benefits from the partial electron occupied egorbitals.This distinct electron configuration(t2_(g)^(5) e_(g)^(1))with unpaired electrons leads to orbital degeneracy,that the adsorption free energy of intermediate species and conductivity were further optimized.The optimized electrocatalyst exhibits excellent OER activity with an overpotential of 268 m V at 10 m A cm^(-2).DFT calculations show that plasma treatment can effectively regulate the d-band center of TMs to optimize the adsorption and improve the OER activity.This approach could guide the rational design and discovery of electrocatalysts with ideal electron configurations in the future.