For the last 20 years, I have been focused on the synthesis and medical & energy applications of uniform-sized nanocrystals and related nanomaterials (Nature Mater. 2004, 3, 891). We reported that uniform 2 nm iron oxide nanoclusters can be successfully used as T1 MRI contrast agent for high-resolution MR angiography of monkeys (Nature Biomed. Eng. 2017, 1, 637). We demonstrated that ceria nanoparticles and ceria–zirconia nanoparticles can work as therapeutic antioxidants to treat various nasty diseases including ischemic stroke, Alzheimer’s disease, sepsis, and Parkinson’s disease (Angew. Chem. Int. Ed. 2012, 51, 11039; ACS Nano, 2016, 10, 2860; Angew. Chem. Int. Ed. 2017, 56, 11399; Angew. Chem. Int. Ed. 2018, 57, 9408; Adv. Mater. 2018, 30, 1807965). CeO₂/Mn₃O₄ nanocrystals possessing surface strains protect tissue-resident stem cells from irradiation-induced ROS damage, significantly increasing the survival rate of the animals (Adv. Mater. 2020, 32, 2001566). We report a highly sensitive and selective K⁺ nanosensor that can quantitatively monitor extracellular K⁺ concentration changes in the brains of freely moving mice experiencing epileptic seizures (Nature Nanotech. 2020, 15, 321).

We present a synthesis of highly durable and active electrocatalysts based on ordered fct-PtFe nanoparticles and FeP nanoparticles coated with N-doped carbon shell (J. Am. Chem. Soc. 2015, 137, 15478; J. Am. Chem. Soc., 2020, 142, 14190; J. Am. Chem. Soc. 2017, 139, 6669). We also report on the design and synthesis of highly active and stable Co-N₄(O) moiety incorporated in nitrogen-doped graphene (Co₁-NG(O)) that exhibits a record-high kinetic current density (2.84 mA cm^-2 at 0.65 V vs. RHE) and mass activity (277.3 A g^-1 at 0.65 V vs. RHE) with unprecedented stability (>110 h) for electrochemical hydrogen peroxide (H₂O₂) production (Nature Mater. 2020, 19, 436). We report on the design and synthesis of highly active TiO₂ photocatalysts incorporated with site-specific single copper atoms (Cu/TiO₂) that exhibit reversible & cooperative photoactivation process, and enhancement of photocatalytic hydrogen generation activity (Nature Mater. 2019, 18, 620). We synthesized multigrain nanocrystals consisting of Co₃O₄ nanocube cores and Mn₃O₄ shells. At the sharp edges of the Co₃O₄ nanocubes, we observed that tilt boundaries of the Mn₃O₄ grains exist in the form of disclinations, and we obtained a correlation between the defects and the resulting electrocatalytic behavior for the oxygen reduction reaction (Nature 2020, 359, 577).