Peng Han

Unconventional mesoporous single crystalline NiO by synergistically controlled evaporation and hydrolysis

Constructing mesoporous single crystals is largely limited due to the challenge of controlling the assembly of nanocrystal building blocks via a conventional evaporation-induced self-assembly process. Here, we developed a facile synergistically controlled evaporation and hydrolysis method to prepare mesoporous single crystal NiO nanorod arrays. The crystallinity of mesoporous NiO is readily tuned from polycrystalline to single crystalline by controlling the evaporation and hydrolysis rates of precursor solvents.

Defective graphene for electrocatalytic CO2 reduction

The rational synthesis of earth-abundant materials with excellent electrocatalytic performances plays a critical role in electrochemical CO2 reduction (ECR) to obtain value-added chemical products or fuels. Here we demonstrate a defective graphene (DG) as such an electrocatalyst candidate via a nitrogen removal method. The graphene with a large amount of topological defects offered abundant catalytically active sites, high electronic conductivity and strong adsorption of CO2. Attributed to these features, the DG exhibited significantly higher electrocatalytic CO2 reduction performances with an excellent faradaic efficiency of ∼84% at -0.6u202fV vs. reversible hydrogen electrode and a larger current density, compared to pristine graphene, nitrogen-doped graphene and edge-rich graphene. This work suggests a promising method for further designing efficient metal-free electrocatalysts for CO2 reduction.

Mesoporous tin oxide for electrocatalytic CO2 reduction

The increasing accumulation of CO2 in the atmosphere has been leading to serious environmental problems. Electrochemical reduction of CO2 is a potential means of carbon recycling for energy storage and environmental sustainability. However, it is limited by the lack of highly active and selective electrocatalysts. Here we demonstrate the development of mesoporous tin oxide (SnO2) for electrocatalytic CO2 reduction, which facilitates the adsorption and electrochemical reduction of CO2 inside mesopores. The highly-ordered and uniform pore sizes of the mesoporous SnO2 electrocatalyst favor the enhancement of formation of carbon monoxide (CO) and formate during the electrochemical reduction. The combined faradaic efficiencies of CO and formate reach a peak value of ∼80% at a current density of 5u202fmAu202fcm-2 at -0.8u202fV vs. reversible hydrogen electrode. This work suggests attractive development of mesoporous electrocatalysts with a variety of pore size and structures for efficient energy conversion and electrochemical CO2 reduction.