硫掺杂氮化碳纳米片棒状聚集体用于光催化析氢

Rod-shaped aggregates of sulfur-doped carbon nitride nanosheets for enhanced photocatalytic hydrogen evolution

合成具有较宽吸收光谱的少层氮化碳是一个具有吸引力的课题.杂原子掺杂(特别是硫掺杂)可以有效地避免纳米级片层氮化碳中由于量子限制效应所引起的带隙加宽.与二次煅烧硫化不同的是,预硫化超分子前驱体可以原位地形成硫掺杂氮化碳纳米片堆叠聚集体(SCN).这种少层的框架结构呈现出了更大的比表面积(139.06 m^(2)g^(−1)),暴露了更多的活性位点.此外,硫的引入使原七嗪环的共轭结构发生扭曲,从而通过激活价带电子的n→π*跃迁而缩小带隙.在模拟日光条件下,SCN0.8(3925.8μmol g^(−1)h^(−1))的析氢速率是块体氮化碳(BCN,485.2μmol g^(−1)h^(−1))的8.1倍.本工作旨在最大限度地利用杂原子掺杂和形态调控的协同效应来提高光催化活性,且为光催化剂的多维同步优化提供了新的视角.

Synthesis of few-layer carbon nitride with wide absorption spectra is an interesting research area.Heteroatom doping,particularly sulfur(S)doping,can effectively prevent band gap widening triggered by the quantum confinement effect in nanoscale carbon nitride sheets.Herein,different from that in second calcination sulfuration,the presulfuration supramolecular precursors can in situ form the S-doped carbon nitride(SCN)nanosheet stacked microrods.This fewlayer frame construction possesses a large specific surface area(139.06 m2 g−1),exposes more active sites,and facilitates the internal reflection of photons.Furthermore,the introduction of S distorts the conjugated structure of the original heptazine ring,narrowing the band gap of carbon nitride through the activation of the n→π*transition in valence band electrons.Consequently,the light absorption range is extended to 700 nm.Finally,the hydrogen evolution rate of SCN0.8(3925.8μmol g^(−1)h^(−1))is 8.1 times that of bulk carbon nitride(485.2μmol g^(−1)h^(−1))under simulated sunlight conditions(AM 1.5G).The stacking of sheets avoids the accumulation of nanosheets and enhances performance and structural stability.The proposed structure aims to maximize the utilization of synergistic effects of heteroatom doping and morphology regulation to improve photocatalytic hydrogen evolution.Furthermore,this work provides a new perspective for the multidimensional synchronous optimization of photocatalysts.