A comparison study of sodium ion- and potassium ion-modified graphitic carbon nitride for photocatalytic hydrogen evolution

Abstract

The ion size effect on graphitic carbon nitride is responsible for variations in its structure, optical and electronic properties, and hence the enhancement in photocatalytic hydrogen evolution.

Unravelling the doping effect of potassium ions on structural modulation and photocatalytic activity of graphitic carbon nitride

“… 32 As shown in Fig. 4(a) , the intensity ratio of 707 cm −1 peak to 725 cm −1 peak apparently decreases for K + -doped GCNs at 530 °C in comparison with that of GCN, suggesting the stronger structure perturbation by K + , 21 which is in line with their corresponding XRD data in Fig. 2(a) .…”

“…Electrochemical measurements including Mott–Schottky curve, transient photocurrent response and electrochemical impedance spectroscopy (EIS) were performed on an electrochemical workstation (CHI-660D, Shanghai Chenhua) with a conventional three-electrode cell, which have been demonstrated in detail previously. 21 A Pt wire was used as a counter electrode, and Ag/AgCl (3.0 M KCl) was used as a reference electrode. To prepare the working electrode, 10 mg sample was dispersed in a 200 μL Nafion solution (5 wt%) to get a slurry, and the as-prepared slurry was dropped onto the platinum–carbon electrode, and then dried under an infrared lamp.…”

“…According to the reported procedure, 21 the photocatalytic H 2 evolution rate of the sample was measured. In detail, 20 mg of photocatalyst was dispersed in 100 mL aqueous solution, containing 10 vol% TEOA (triethanolamine).…”

“…According to the previous studies, the influence of K + on GCN is manifested in the aspects of changing morphology, 12,26 introducing new functional groups, 13,17 tuning electronic band structure, 14 narrowing band gap, 15,16 or modulating crystallinity, 10–13,18,21,25 etc. However, most studies about K + -doped GCN showed only partial doping effects.…”

“…5,6,8,9 K + is one of the most studied elements among metal ion doping GCN studies. K + -doped GCN is usually obtained through potassium halide assisted thermal polymerization of nitrogenrich precursor, [10][11][12][13][14][15][16][17][18][19][20][21][22][23] and a few reports directly using GCN as the precursor. [24][25][26][27] The calcination temperature was oen set at 550 °C, the same temperature at which the pristine GCN was prepared.…”