Developing Ideal Metalorganic Hydrides for Hydrogen Storage: From Theoretical Prediction to Rational Fabrication

Published

September 6, 2021

Author(s)

Zijun Jing, Qinqin Yuan, Yang Yu, Xiangtao Kong, Khai C. Tan, Jintao Wang, Qijun Pei, Xue-Bin Wang, Wei Zhou, Hui Wu, Anan Wu, Teng He, Ping Chen

Abstract

Materials for hydrogen storage have been extensively explored for a few decades. Thousands of hydrogen storage materials have been synthesized and tested, however, sparse systems could meet the practical requirements. Metalorganic hydrides discovered recently offer new opportunity. It is, however, extremely time-consuming and inefficient to experimentally screen potential materials from a large variety of metal cations and organic anions. In the present study, we performed wide-ranging theoretical prediction and screened more than 90 metalorganic hydrides, 20 of them were identified with both high hydrogen capacities (≥5 mass %) and suitable thermodynamics (heat of H₂ desorption: 25 35 kJ/mol) that allows hydrogen uptake and release near ambient condition. We picked up four of them, i.e., Li/Na indolides and 7-azaindolides for experimental validation. All the four candidates can be easily synthesized via the reactions between metal hydrides and corresponding organic precursors. Among them the structures of lithium indolide (P2_1/c(no. 14)) and sodium 7-azaindolide (P-42_1c(no. 114) were successfully resolved. Photoelectron spectroscopy and quantum chemical calculations confirmed that charge density of organics ring increased with the introduction of alkali metal, thus optimizing their ΔHd for hydrogen storage. Importantly, we demonstrated experimentally that lithium indolide has a heat of hydrogen absorption of ca. 33.7 kJ/mol which is in excellent agreement with the value (33.6 kJ/mol) predicted theoretically. This compound can reversibly store 6.1mass % of hydrogen at 100 °C. These results illustrate the great potential of metalorganic hydrides for tackling the grand challenge of hydrogen storage and manifest the effectiveness of theoretical prediction in guiding materials fabrication.

Citation

ACS Materials Letters

Volume

3

Issue

9

Pub Type

Journals

Keywords

Hydrogen storage, hydrides, X-ray diffraction, First-principles calculations.

Citation

Jing, Z. , Yuan, Q. , Yu, Y. , Kong, X. , Tan, K. , Wang, J. , Pei, Q. , Wang, X. , Zhou, W. , Wu, H. , Wu, A. , He, T. and Chen, P. (2021), Developing Ideal Metalorganic Hydrides for Hydrogen Storage: From Theoretical Prediction to Rational Fabrication, ACS Materials Letters (Accessed April 24, 2024)