Single-source-precursor synthesis of porous W-containing SiC-based nanocomposites as hydrogen evolution reaction electrocatalysts

Zhaoju Yu,Yao Feng,Kangwei Mao

doi:10.1007/s40145-021-0508-8

Abstract

In this paper, W-containing SiC-based ceramic nanocomposites were successfully prepared by a polymer-derived ceramic approach using allylhydridopolycarbosilane (AHPCS) as a SiC source, WCl6 as a tungsten source, polystyrene (PS) as a pore forming agent as well as divinyl benzene (DVB) as a carbon rich source. High-temperature phase behavior of the W-containing SiC-based ceramics after heat treatment was studied, showing that excessive DVB content in the feed will inhibit the crystallinity of W-containing nanoparticles in the final ceramic nanocomposites. The high specific surface area (SSA) of 169.4–276.9 m2/g can be maintained even at high temperature in the range of 1400–1500 °C, due to the carbothermal reaction which usually occurs between 1300 and 1400 °C. All prepared W-containing SiC-based nanocomposites reveal electrocatalytic activity for the hydrogen evolution reaction (HER). In detail, compared with reversible hydrogen electrode (RHE), the ceramic sample PWA-2-1300 after heat treatment at 1300 °C has the smallest overpotential of 286 mV when the current density is 10 mA·cm−2 in acid medium, indicating the promising perspective in the water splitting field.

Highlights

Polymer-derived ceramic (PDC) approach started from the 1960s and is a versatile method used for the fabrication of mainly Si-based advanced ceramics [1,2]
It is worth mentioning that compared with original AHPCS and DVB, the C–H stretch of –CH=CH2 at 3078 and 3090 cm–1 together with the C=C stretch in 1630 cm–1 disappear in the sample PWA-3-RT
Since the characteristic absorption peaks of C=C already disappear at the room temperature (PWA-3-RT), the weaker absorption intensity of Si–H must be due to the dehydrochlorication reaction between WCl6 and remaining Si–H, based on the findings that the dehydrochlorication reaction can occur between metal chlorides and Si–H groups [8,9]

Summary

Introduction

Polymer-derived ceramic (PDC) approach started from the 1960s and is a versatile method used for the fabrication of mainly Si-based advanced ceramics [1,2]. Despite platinum-group metal (such as Pt, Ru, Rh, Ir, and Pd) has been reported as outstanding and stable cathode catalysts for HER in both acidic and alkaline electrolytes, its practical applications for electrochemical water splitting are still very limited because of its high cost [26,27]. For pure transition metal carbides, such as tungsten carbides, it is still difficult to synthesize a nanosized structure with high SSA, which decreases active sites and hinders the diffusions of ions, electrolyte, and generated gas [32]. To further extend the application of PDCs in the field of water splitting, for the first time, we successfully synthesized W-containing SiC-based nanocomposites used as HER electrocatalysts by PDC approach using allylhydridopolycarbosilane (AHPCS) as a SiC source and tungsten hexachloride (WCl6) as a tungsten source [36]. The phase transformation of W-containing SiC-based nanocomposites annealed at 900–1500 °C were studied in detail

Experimental

Results and discussion

Conclusions