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In situ construction of hierarchical graphitic carbon nitride homojunction as robust bifunctional photoelectrocatalyst for overall water splitting
Author(s) -
Luo Leng,
Zhang HuaWei,
Han ErXun,
Zhou BinXin,
Huang WeiQing,
Hu Wangyu,
Huang GuiFang
Publication year - 2020
Publication title -
journal of chemical technology and biotechnology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.64
H-Index - 117
eISSN - 1097-4660
pISSN - 0268-2575
DOI - 10.1002/jctb.6261
Subject(s) - tafel equation , homojunction , overpotential , water splitting , oxygen evolution , materials science , graphitic carbon nitride , catalysis , bifunctional , chemical engineering , inorganic chemistry , photocatalysis , chemistry , electrochemistry , electrode , doping , optoelectronics , engineering , biochemistry
BACKGROUND Sustainable production of oxygen and hydrogen via catalyst‐aided water splitting utilizing solar energy has attracted increasing interest. The primary issue in this field is the development of earth‐abundant and active photoelectrocatalytic materials. Herein, a novel hierarchical g‐C 3 N 4 /g‐C 3 N 4 metal‐free homojunction catalyst is synthesized through partial hydrolysis of melamine in alkali and subsequent thermal treatment. RESULTS The hierarchical g‐C 3 N 4 /g‐C 3 N 4 metal‐free homojunction composed of lamellas features large exposed surface area, abundant interface contact and more channels for mass transfer, making it highly effective for water splitting with a small overpotential of 500 mV at 10 mA cm −2 and low Tafel slope of 93.1 mV dec −1 for oxygen evolution reaction (OER) in 1.0 mol L −1 potassium hydroxide (KOH) solution, as well as 259 mV at 10 mA cm −2 and 109.33 mV dec −1 for hydrogen evolution reaction (HER) in 0.5 mol L −1 sulfuric acid (H 2 SO 4 ) solution. Furthermore, the overpotential and Tafel slope further decrease to 383.4 mV and 69.52 mV dec −1 for OER, 150.1 mV and 67.93 mV dec −1 for HER upon visible light irradiation, demonstrating the exceptional photo‐responsive catalytic performance, which can be attributed to the direct Z‐scheme homojunction resulting in effective charge transfer and •OH and superoxide free radicals produced under visible light irradiation. CONCLUSION This work provides a facile but effective approach for the construction of metal‐free OER/HER bifunctional catalyst with high photo‐responsive performance, achieving higher activity for catalyst‐assisted water splitting. © 2019 Society of Chemical Industry