Self-healing hydrogels have a great potential application in 3D printing, soft robotics, and tissue engineering. There have been a large number of successful strategies for developing hydrogels that exhibit rapid and autonomous recovery. However, developing a gel with an excellent self-healing performance within several seconds is still an enormous challenge. Here, an ultrafast self-healing hydrogel based on an agarose/PVA double network (DN) is presented. The gel utilizing a dynamic borate bond exhibits 100% cure in strength and elongation after healing for 10 s in air, and this hydrogel shows an excellent self-healing property underwater as well. In addition, the agarose/PVA DN hydrogel exhibits a smart self-healing property for an in situ priority recovery, ensuring that the shape and the function are the same as those of the original one. With the combination of self-healing properties, such a hydrogel could be applied to a board range of areas.

Molecular-scale modulation of interfaces between different unilamellar nanosheets in superlattices is promising for efficient catalytic activities. Here, three kinds of superlattices from alternate restacking of any two of the three unilamellar nanosheets of MoS 2 , NiFe-layered double hydroxide (NiFe-LDH), and graphene are systematically investigated for electrocatalytic water splitting. The MoS 2 /NiFe-LDH superlattice exhibits a low overpotential of 210 and 110 mV at 10 mA cm −2 for oxygen evolution reaction (OER) and alkaline hydrogen evolution reaction (HER), respectively, superior than MoS 2 / graphene and NiFe-LDH/graphene superlattices. High activity and stability toward the overall water splitting are also demonstrated on the MoS 2 /NiFe-LDH superlattice bifunctional electrocatalyst, outperforming the commercial Pt/C-RuO 2 couple. This outstanding performance can be attributed to optimal adsorption energies of both HER and OER intermediates on the MoS 2 /NiFe-LDH superlattice, which originates from a strong electronic coupling effect at the heterointerfaces. These results herald the interface modulation of superlattices providing a promising approach for designing advanced electrocatalysts.

Electrocatalytic denitrification is a promising technology for removing NOx species (NO3−, NO2− and NO). For NOx electroreduction (NOxRR), there is a desire for understanding the catalytic parameters that control the product distribution. Here, we elucidate selectivity and activity of catalyst for NOxRR. At low potential we classify metals by the binding of *NO versus *H. Analogous to classifying CO2 reduction by *CO vs. *H, Cu is able to bind *NO while not binding *H giving rise to a selective NH3 formation. Besides being selective, Cu is active for the reaction found by an activity‐volcano. For metals that does not bind NO the reaction stops at NO, similar to CO2‐to‐CO. At potential above 0.3 V vs. RHE, we speculate a low barrier for N coupling with NO causing N2O formation. The work provides a clear strategy for selectivity and aims to inspire future research on NOxRR.

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