One‐Step Approach for Constructing High‐Density Single‐Atom Catalysts toward Overall Water Splitting at Industrial Current Densities

The construction of highly active, durable, and cost-effective catalysts is urgently needed for green hydrogen production. Herein, catalysts consisting of high-density Pt (24 atoms nm-2 ) and Ir (32 atoms nm-2 ) single atoms anchored on Co(OH)2 were constructed by a facile one-step approach. Remarkably, Pt1 /Co(OH)2 and Ir1 /Co(OH)2 only required 4 and 178 mV at 10 mA cm-2 for hydrogen evolution reaction and oxygen evolution reaction, respectively. Moreover, the assembled Pt1 /Co(OH)2 //Ir1 /Co(OH)2 system showed mass activity of 4.9 A mgnoble metal-1 at 2.0 V in an alkaline water electrolyzer, which is 316.1 times higher than that of Pt/C//IrO2 . Mechanistic studies revealed that reconstructed Ir-O6 single atoms and remodeled Pt triple-atom sites enhanced the occupancy of Ir-O bonding orbitals and improved the occupation of Pt-H antibonding orbital, respectively, contributing to the formation of the O-O bond and the desorption of hydrogen. This one-step approach was also generalized to fabricate other 20 single-atom catalysts.