Controlling atomic phosphorous-mounting surfaces of ultrafine W_(2)C nanoislands monodispersed on the carbon frameworks for enhanced hydrogen evolution  

可控表面磷原子修饰提升超细W_(2)C纳米颗粒电解水析氢反应性能

作　　者：Xiangyong Zhang Tianying Liu Ting Guo Xueying Han Zongyun Mu Qiang Chen Jiangmin Jiang Jing Yan Jiaren Yuan Dezhi Wang Zhuangzhi Wu Zongkui Kou 张祥勇;刘添滢;郭挺;韩雪莹;木宗云;陈强;蒋江民;闫婧;袁加仁;王德志;吴壮志;寇宗魁(中南大学材料科学与工程学院,湖南长沙410083;武汉理工大学材料复合新技术国家重点实验室,湖北武汉430070;江苏大学物理与电子工程学院,江苏镇江212013)

机构地区：[1]School of Materials Science and Engineering,Central South University,Changsha 410083,Hunan,China [2]State Key Laboratory of Advanced Technology for Materials Synthesis and Processing,Wuhan University of Technology,Wuhan 430070,Hubei,China [3]School of Physics and Electronic Engineering,Jiangsu University,Zhenjiang 212013,Jiangsu,China

出　　处：《Chinese Journal of Catalysis》2021年第10期1798-1807,共10页催化学报（英文）

基　　金：国家自然科学基金(51572301);国家重点研发项目(2017YFB0306000);湖南省自然科学基金(2016JJ3153);中南大学创新驱动项目(502221802);中南大学双一流资助项目.

摘　　要：Controllably mounting foreign atoms on the surfaces of earth-abundant electrocatalysts strongly improve their surface electronic properties for optimizing the catalytic performance of surficial sites to an unusual level,and provides a good platform to gain deep insights into catalytic reactions.The present work describes,employing ultrafine W2C nanoislands(average size:2.3 nm)monodispersed on the N,P dual-doped carbon frameworks as a model system,how to regulate the atomic phosphorous-mounting effect on the surfaces of W_(2)C to derive an active and stable P-mounting W_(2)C(WCP)catalyst for both acidic and alkaline hydrogen evolution reaction(HER).Since in situ phosphorus substitution into carbon sites of preformed W_(2)C nanoislands gradually proceeds from surfaces to solids,so that using a proper amount of phosphorus sources can readily control the surface mounting level to avoid the mass P-doping into the bulk.By this way,the activity per active site of WCP catalyst with robust stability can be optimized to 0.07 and 0.56 H_(2 )s^(-1) at-200 mV overpotential in acid and base,respectively,which reach up to the several-fold of pure-phase W_(2)C(0.01 and 0.05 H_(2) s^(-1)).Theoretical investigations suggest that compared with solid P doping,the P mounting on W_(2)C surface can more remarkably enhance its metallicity and decrease the hydrogen release barrier.This finding disclosed a key correlation between surface foreign atom-mounting and catalytic activity,and suggested a logical extension to other earth-abundant catalysts for various catalytic reactions.研究高活性和稳定性的非贵金属基析氢催化剂对解决当前能源危机和环境污染问题具有重要意义.碳化鹄具有与贵金属Pt类似的d带电子结构,因而成为一类新兴的非贵金属析氢催化剂,受到广泛关注.磷掺杂是提高催化剂析氢活性的有效方法之一,然而目前最常见的构筑磷掺杂方法是使用多金属氧酸盐(POMs,如H3PW_(12)O_(40)),其固定的W/P原子比导致W_(2)C中的掺杂浓度难以调控,并且磷掺杂主要是进入碳载体而不是碳化物本身,从而导致无法明确杂原子对其电催化析氢活性的贡献.本文采用植酸(PA)为磷源设计合成了可控磷掺杂W_(2)C纳米颗粒,并探讨了催化剂组分、杂原子掺杂位置与析氢性能之间的关系.深入研究了磷掺杂碳化钨(WCP)的化学结构和析氢活性.与原始的W_(2)C催化剂相比,WCP具有更高的本征活性、更快的电子转移速率和更多的活性位数量,并且在酸性和碱性条件下均表现出较好的析氢性能.特别是过电位为-200 mV时,WCP催化剂的本征活性在酸性和碱性条件下分别为0.07和0.56H_(2)s^(-1),高出纯W_(2)C(0.01和0.05 H_(2)s^(-1))数倍.同时,在电流密度为-10mA cm^(-2)时,优化后的WCP催化剂在酸性和碱性条件下的析氢过电位分别降低了96和88 mV.XPS及EDS元素分析结果表明,随磷源添加量增加,磷掺杂从碳化钨表面逐渐向内部扩散,进一步说明磷取代位置与析氢活性之间的构效关系,高浓度的表面磷取代可以加速质子捕获过程,从而显著提高其析氢活性,而过量的内部磷取代会破坏W_(2)C结构,降低电子转移速率,从而导致析氢性能下降.利用密度泛函理论计算深入研究了WCP具有较好析氢性能的原因,与内部磷取代相比,表面磷取代会使碳化钩表现出更合适的氢吸附自由能,并且更加有效地降低了氢释放势垒,从而优化了析氢反应动力学.综上,本文为元素掺杂工艺提供了新的思路,同时研究了表面�

关 键 词：Tungsten carbide Doping Surficial engineering Hydrogen evolution reaction ELECTROCATALYST 

分 类 号：TQ116.2[化学工程—无机化工] TQ426[一般工业技术—材料科学与工程] TB383.1