Enhanced Hydrogen Evolution Catalysis of Pentlandite due to the Increases in Coordination Number and Sulfur Vacancy during Cubic-Hexagonal Phase Transition

TL;DR

This paper reports the discovery of a new hexagonal phase of pentlandite with enhanced catalytic properties for hydrogen evolution, driven by increased sulfur vacancies and coordination number during a phase transition.

Contribution

It introduces the sulfur-vacancy enriched hexagonal pentlandite phase and details its superior catalytic performance compared to cubic pentlandite, highlighting a new design approach.

Findings

hPn exhibits higher conductivity than cPn

hPn has more sulfur vacancies and higher coordination number

hPn outperforms cPn and other nanosulfide catalysts in hydrogen evolution

Abstract

The search for new phases is an important direction in materials science. The phase transition of sulfides results in significant changes in catalytic performance, such as MoS2 and WS2. Cubic pentlandite [cPn, (Fe, Ni)9S8] can be a functional material in batteries, solar cells, and catalytic fields. However, no report about the material properties of other phases of pentlandite exists. In this study, the unit-cell parameters of a new phase of pentlandite, sulfur-vacancy enriched hexagonal pentlandite (hPn), and the phase boundary between cPn and hPn were determined for the first time. Compared to cPn, the hPn shows a high coordination number, more sulfur vacancies, and high conductivity, which result in significantly higher hydrogen evolution performance of hPn than that of cPn and make the non-nano rock catalyst hPn superior to other most known nanosulfide catalysts. The increase of sulfur vacancies during phase transition provides a new approach to designing functional materials.