Photoelectrochemical Properties of α ‐ and   β ‐ ZnP2 Electrodes and Powders

Abstract

The basic photoelectrochemical behavior of tetragonal p‐type α‐ZnP2 has been investigated for the first time. The photoinduced current as a function of applied voltage and the spectral distribution of the photoresponse were measured in alkaline solutions (pH 13). Photosensitivity up to 580 nm in the visible range of the spectrum has been observed. From a linear Mott‐Schottky relation, an approximate value of the flatband potential false(VFB=−0.7±0.05 VSCEfalse) at pH 13 for monoclinic β‐ZnP2 has been determined. As a function of pH, VFB shows Nernstian behavior. For tetragonal α‐ZnP2 , VFB could not be determined. The onset of the cathodic photocurrent ( ≈−0.4 VSCE at pH 13) indicates, however, a somewhat more positive VFB for α‐ZnP2 . Upon illumination with visible light, hydrogen evolution from alkaline EDTA solutions containing ZnP2 powders loaded with a catalyst is very efficient. For α‐ZnP2 loaded with 0.5 weight percent of RuO2 , a formal quantum efficiency of 12% is found at 470 nm.

Zinc Phosphides as Outstanding Sodium-Ion Battery Anodes

“…The binary Zn–P system has various compounds and polymorphs, such as ZnP 2 (α-tetragonal, β-cubic, monoclinic), Zn 3 P 2 (α-tetragonal, β-cubic), and ZnP 4 (monoclinic) . Thanks to their interesting characteristics and various crystalline structures, they have been studied widely for optoelectronics, semiconductors, photovoltaic devices, and Schottky diodes. , Furthermore, binary zinc phosphides have been applied as LIB anode materials because of the high theoretical capacities of ZnP 2 (1474 mA h g –1 ), Zn 3 P 2 (934 mA h g –1 ), and ZnP 4 (1841 mA h g –1 ). − Considering their wide use in LIB applications and high theoretical capacities (ZnP 2 : 1279 mA h g –1 , Zn 3 P 2 : 647 mA h g –1 ) for SIBs, zinc phosphides also can be applied as high-capacity SIB anode materials. However, zinc phosphides have hitherto not received any attention as new SIB anode materials.…”