Electrocatalytic Hydrogen Evolution of Bent Bis(dipyrrin) Ni(II) Complexes

Songlin Xue; Xiaojuan Lv; Ningchao Liu; Qingxin Zhang; Haitao Lei; Rui Cao; Fengxian Qiu

doi:10.1021/acs.inorgchem.2c04097

Electrocatalytic Hydrogen Evolution of Bent Bis(dipyrrin) Ni(II) Complexes

Inorg Chem. 2023 Jan 30;62(4):1679-1685. doi: 10.1021/acs.inorgchem.2c04097. Epub 2023 Jan 12.

Authors

Songlin Xue¹, Xiaojuan Lv¹, Ningchao Liu¹, Qingxin Zhang², Haitao Lei², Rui Cao², Fengxian Qiu¹

Affiliations

¹ School of Chemistry and Chemical Engineering, Jiangsu University, 301 Xuefu Road, Zhenjiang 212013, China.
² Key Laboratory of Applied Surface and Colloid Chemistry, Ministry of Education, School of Chemistry and Chemical Engineering, Shaanxi Normal University, Xi'an 710119, China.

PMID: 36634365
DOI: 10.1021/acs.inorgchem.2c04097

Abstract

Planar Ni(II) porphyrinoid complexes have been widely used in electrochemical carbon dioxide reduction reaction and oxygen reduction reaction as well as hydrogen evolution reaction (HER). However, nonplanar Ni(II) tetra-pyrrolic complexes have not been thoroughly investigated thus far. In this study, three highly bent bis(dipyrrin) Ni(II) complexes have been synthesized to investigate their structure, electronic property, and electrocatalytic HER activities. Cyclic voltammetry and thin-layer UV-visible spectroelectrochemistry studies revealed four redox processes, yielding two reduced species as the final products. The i_c/i_p values of phenyl- and pentafluorophenyl-bearing bis(dipyrrin) Ni(II) complexes were >30 when trifluoroacetic acid was used as the proton source, and their Faradaic efficiencies for H₂ generation were >93%. Density functional theory calculations of the HERs revealed low endothermic energies of bent bis(dipyrrin) Ni(II) complexes.