Highly Efficient Synthesis of Hydrogen Storage Material of Formate from Bicarbonate and Water with General Zn Powder

Formate, as an excellent hydrogen-storage material, has recently become increasingly important because formate has low toxicity, is easy to store and transport, and contains relatively high energy density. In this paper, we give an overview of the recent strategies in the conversion of bicarbonate into formate by water splitting with a general metallic Zn powder, which mainly includes: (1) hydrogen production from water with Zn; (2) formate syntheses from bicarbonate with water-derived hydrogen; (3) catalytic role of ZnO and Zn/ZnO interface and reducing role of active intermediate of Zn hydride species (Zn-H); (4) density function theory calculation for formate synthesis from bicarbonate and water with Zn; (5) solar-to-chemical energy conversion efficiency estimation. The novel options of this proposed strategy are mainly the hydrogen being in situ formed from water with metal Zn as a reductant, and the plausible autocatalytic reaction mechanism. When coupled with reducing ZnO into Zn by solar energy, a highly efficient solar-fuel process can be expected.