%0 Journal Article
%T <br>
%A 刘佳
%A 吕亮
%A 张绍政
%A 李林
%A 杨建辉
%A 谢燕
%A 陆银稷
%A 韦世豪
%J 物理化学学报
%D 2017
%R 10.3866/PKU.WHXB201705174
%X MXene是一种新型的二维析氢催化材料，其表面容易被亲水基团O和OH混合覆盖。我们基于第一性原理计算的方法，研究了M2XO2-2x（OH）2x（M=Ti，V；X=C，N）的析氢催化活性。计算结果显示，M2XO2-2x（OH）2x的析氢催化活性与其表面OH覆盖率（x）密切相关。对Ti2CO2-2x（OH）2x来说，OH覆盖率不超过1/3时，具有优异的析氢催化活性。对Ti2NO2-2x（OH）2x、V2CO2-2x（OH）2x和V2NO2-2x（OH）2x来说，OH覆盖率分别达到4/9、1/3和5/9时，才具有最佳的析氢催化活性。接着，电荷分析显示OH覆盖率会显著影响M2XO2-2x（OH）2x活性位点O基团的电荷量。最后，我们从态密度的角度揭示了析氢催化活性变化的原因，即活性位点O基团的氧化性随OH覆盖率的增大而被削弱。因此，本文提出了调节表面OH覆盖率来获取M2XO2-2x（OH）2x最佳析氢催化活性状态的方法，这在工业制氢生产过程中具有重要的应用价值。<br>MXene is a new group of electrocatalysts for two-dimensional hydrogen evolution reaction (HER). Its surfaces are often covered by hydrophilic O and OH mixed groups. To find the effect of the O and OH mixed groups on HER, we studied the HER activity for M2XO2-2x(OH)2x (M=Ti, V; X=C, N) by first-principle calculations. Results indicate that HER activity is closely related to OH-occupied coverage (x). For Ti2CO2-2x(OH)2x, excellent HER activity could be maintained when the OH-occupied coverage was not larger than 1/3. For Ti2NO2-2x(OH)2x, V2CO2-2x(OH)2x, and V2NO2-2x(OH)2x, high HER activity was obtained when OH-occupied coverage reached 4/9, 1/3, and 5/9, respectively. Next, we analyzed the charge-transfer density and found that the charges on the oxygen groups were strongly affected by the OH-occupied coverage. Finally, we revealed the variation of HER activity that oxidizability of O groups is weakened with increasing OH-occupied coverage. In this paper, we propose a new method to obtain the optimal HER activity for M2XO2-2x(OH)2x by adjusting the OH-occupied coverage of the surfaces, which is useful in industrial hydrogen production
%U http://www.whxb.pku.edu.cn/CN/Y2017/V33/I10/2022