掺氮WO2.83的制备及其电催化析氢性能

Preparation of nitrogen-doped WO2.83 catalyst for hydrogen evolution reaction

WO 2.83因其晶体结构中有大量的氧缺陷而被广泛应用于光催化研究,但是由于制备困难、催化活性低导致其在电催化析氢领域应用较少。利用磷钨酸(PWA)和十六烷基三甲基溴化铵(CTAB)得到不同的前驱体,再通过一步煅烧法分别成功制备得到纯相WO 2.83和氮掺杂相WO 2.83|WN。通过透射电镜(TEM)和X射线晶体衍射(XRD)结果发现:PWA和CTAB物理混合前驱体经煅烧后可以得到纯相WO 2.83,而由PWA和CTAB自组装后形成的前驱体经煅烧可以得到氮掺杂WO 2.83|WN。电化学测试表明:该催化剂在达到10 mA/cm 2电流密度下所需过电位为116 mV,远低于纯相WO 2.83,且电化学活性表面积(ECSA)是纯相WO 2.83的15倍,分析认为WO 2.83|WN催化析氢性能提高是因为氮原子的引入调节了中心金属钨的电子结构,增强了本体的催化活性,从而使得析氢性能得到优化。

WO 2.83 has attracted great interests in photocatalysis owing to its abundant oxygen vacancies,however,its electrocatalytic applications in hydrogen evolution reaction(HER)are not well studied due to its difficult preparations and poor electrocatalytic performances.In this work,pure WO 2.83 and nitrogen-doped WO 2.83 catalysts(WO 2.83|WN)were synthesized by using phosphotungstic acid(PWA)and CTAB as raw materials.TEM and XRD data showed that WO 2.83|WN could be synthesized by calcining surfactant-encapsulated PWAs(PWA-CTAB),while pure WO 2.83 was obtained if the precursor was prepared by physically mixing CTAB and PWA.Results of electrochemical tests showed that the WO 2.83|WN catalyst exhibited higher electrocatalytic activity than pure phase WO 2.83 with an overpotential of 116 mV required to achieve a current density of 10 mA/cm 2 in 0.5 mol/L H 2SO 4.It also showed 15 times larger electrochemical active surface area(ECSA)than that of WO 2.83.The enhanced HER performance was attributed to favorable electron distributions on metal W and increases of active sites introduced from doped nitrogen.