辐射还原-剥离法制备纳米金属/氮化硼纳米片复合催化剂

Preparation of nano-metal/boron nitride nanosheets composite catalyst by a radiation-induced reduction-exfoliation method

在二维材料(TDM)制备领域,从六方氮化硼(h-BN)高效剥离制备氮化硼纳米片(BNNS)仍是一项具有挑战性的工作。本文提出了一种在醇水溶液中辐射诱导还原-剥离(Radiation-induced reductionexfoliation,RIRE)h-BN的新方法。该方法的核心思想是利用插层在h-BN晶体层间的Ni2+离子的原位辐射还原生成Ni纳米粒子过程中产生的体积膨胀效应,破坏h-BN晶体的层间相互作用,从而实现常温常压下,一步从h-BN上剥离出负载着约20 nm镍纳米粒子(NiNP),200 nm见方且厚度小于5 nm的氮化硼纳米片(Ni/BNNS)。所制备的Ni/BNNS表现出纳米镍优异的催化性能,并且具有良好的结构稳定性和磁分离性,可以回收循环利用。更值得注意的是,Ni/BNNS的甲醇/水分散液在模拟阳光照射下可以监测到氢气的生成,2 h内氢气的释放量以Ni质量计量为8404.3μmol/g。这项工作不仅为高效剥离制备BNNS提供了新思路,还为一步法制备新型TDM负载的纳米金属催化剂开辟了新途径,也为可见光催化剂的催化机制提出了新思考。

The fabrication of boron nitride nanosheets(BNNS)by the exfoliation of hexagonal boron nitride(h-BN)remains a challenging task in the field of two-dimensional material(TDM)preparation.Radiation-induced reduction-exfoliation(RIRE)is a new method of preparation of BNNS from h-BN.RIRE is achieved by the disruption of the interlayer interactions in a h-BN crystal by means of the volume expansion caused by the formation of Ni nanoparticles(NiNPs).NiNPs are formed via the radiation reduction of Ni2⁺ions intercalated between the h-BN crystal layers.As a result,sheet-like NiNP(approximately 20 nm)-bound BNNS(Ni/BNNS)in 200 nm squares,with an average thickness of less than 5 nm,was successfully peeled from h-BN under ambient temperature and pressure conditions in an alcohol/water medium.The prepared Ni/BNNS exhibited excellent catalytic performance,good structural stability,and viability for magnetic separation,which make Ni/BNNS recyclable.More notably,when the water/methanol dispersion containing Ni/BNNS was exposed to simulated sunlight irradiation,H2 evolution of 8404.3μmol/g Ni within 2 h was detected.Therefore,this work provides a new means for the preparation of BNNS by the efficient exfoliation of h-BN,introduces a one-step preparation method for novel TDM-supported nano-metal catalysts,and offeres new insight into the catalytic mechanism of visible-light catalysts.