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, Pt 1 /Co(OH) 2 and Ir 1 /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 Pt 1 /Co(OH) 2 //Ir 1 /Co(OH) 2 system showed mass activity of 4.9 A mg noble metal -1 at 2.0 V in an alkaline water electrolyzer, which is 316.1 times higher than that of Pt/C//IrO 2 . Mechanistic studies revealed that reconstructed Ir-O 6 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.