Ni, Co基硒化物修饰g-C3N4光催化产氢研究

doi:10.3866/PKU.WHXB201912033

物理化学学报 >> 2021, Vol. 37 >> Issue (10): 1912033.doi: 10.3866/PKU.WHXB201912033

Ni, Co基硒化物修饰g-C₃N₄光催化产氢研究

靳治良, 李彦兵(), 郝旭强()

北方民族大学化学与化学工程学院，宁夏太阳能化学转化技术重点实验室，国家民委化工技术基础重点实验室，银川 750021

收稿日期:2019-12-11 发布日期:2020-02-03
通讯作者: 李彦兵,郝旭强 E-mail:1757039358@qq.com;haoxuqiang@126.com
基金资助:
国家自然科学基金(21862002);国家自然科学基金(41663012);北方民族大学重大科研项目“清洁能源催化生产中的新技术、新体系”(ZDZX201803);北方民族大学宁夏低品位资源高价值利用与环境化学一体化技术创新团队项目资助

Ni, Co-Based Selenide Anchored g-C₃N₄ for Boosting Photocatalytic Hydrogen Evolution

Zhiliang Jin, Yanbing Li(), Xuqiang Hao()

School of Chemistry and Chemical Engineering, Key Laboratory for Chemical Engineering and Technology, State Ethnic Affairs Commission, Ningxia Key Laboratory of Solar Chemical Conversion Technology, North Minzu University, Yinchuan 750021, China

Received:2019-12-11 Published:2020-02-03
Contact: Yanbing Li,Xuqiang Hao E-mail:1757039358@qq.com;haoxuqiang@126.com
About author:Emails: haoxuqiang@126.com (X.H.); +86-18095117159 (X.H.)
Emails: 1757039358@qq.com (Y.L.); +86-15709611341 (Y.L.)
Supported by:
the Chinese National Natural Science Foundation(21862002);the Chinese National Natural Science Foundation(41663012);the New Technology and System for Clean Energy Catalytic Production, Major Scientific Project of North Minzu University(ZDZX201803);the Ningxia Low-Grade Resource High Value Utilization and Environmental Chemical Integration Technology Innovation Team Project of North Minzu University

摘要/Abstract

摘要：

新型高效的催化剂是突破单体光催化材料载流子低分离和转移效率的重要途径。本文将Ni₃Se₄和CoSe₂纳米粒子锚定在具有良好分散性的g-C₃N₄纳米片表面，合成了两种新的g-C₃N₄@Ni₃Se₄和g-C₃N₄@CoSe₂光催化剂并实现了原位光催化析氢。相当严重的载流子的重组导致g-C₃N₄单体展现了大约只有1.9 μmol·h^-1的极差的光催化析氢活性。Ni₃Se₄和CoSe₂纳米颗粒对于加速载流子快速分离和转移的独特作用使得在g-C₃N₄表面负载Ni₃Se₄和CoSe₂纳米粒子极大地提高了其产氢活性。G-C₃N₄@Ni₃Se₄展示了一个大约16.4 μmol·h^-1的光催化产氢活性并且g-C₃N₄@CoSe₂展现了一个大约25.6 μmol·h^-1的光催化产氢活性，这分别是g-C₃N₄单体的8倍和13倍。其中，将Ni₃Se₄和CoSe₂与g-C₃N₄耦合可以显著提高光吸收密度以及扩展光响应范围。激发态EY在g-C₃N₄@Ni₃Se₄和g-C₃N₄@CoSe₂存在时比在g-C₃N₄存在时展现了更低的荧光强度，并且在g-C₃N₄@Ni₃Se₄和g-C₃N₄@CoSe₂体系中可观察到最大的电子转移速率。相比g-C₃N₄@Ni₃Se₄@FTO和g-C₃N₄@CoSe₂@FTO电极，g-C₃N₄@@FTO显现了最小的光电流响应密度和最大的电化学，这表明在g-C₃N₄纳米片表面引入Ni₃Se₄和CoSe₂纳米颗粒增强了光生载流子的分离和转移效率，即基于g-C₃N₄的金属硒化的合成有效地抑制了光生载流子的复合以及促进了光催化水裂解制氢反应。同时，吸收带边的红移有效地降低了光激电子从价带到导带跃迁的阈值。此外，g-C₃N₄@Ni₃Se₄和g-C₃N₄@CoSe₂复合催化剂的zeta电位比g-C₃N₄的更负，说明样品表面对质子增强的吸附。并且密度泛函理论结果表明：g-C₃N₄中N位点对H的吸附能为-0.22 eV，还发现氢原子更倾向于吸附在两个硒原子的桥位点上形成Se―H―Se键，并且吸附能为1.53 eV。所有对样品进行的透射电子显微镜(TEM)、扫描电子显微镜(SEM)、X射线光电子能谱(XPS)、X射线衍射(XRD)、紫外可见漫反射光谱(UV-Vis-DRS)、瞬态光电流、傅立叶变换红外光谱(FT-IR)等相关表征都展示了彼此匹配的结果。

关键词: Ni₃Se₄, CoSe₂, g-C₃N₄, 析氢

Abstract:

Developing novel and efficient catalysts is a significant way to break the bottleneck of low separation and transfer efficiency of charge carriers in pristine photocatalysts. Here, two fresh photocatalysts, g-C₃N₄@Ni₃Se₄ and g-C₃N₄@CoSe₂ hybrids, are first synthesized by anchoring Ni₃Se₄ and CoSe₂ nanoparticles on the surface of well-dispersed g-C₃N₄ nanosheets. The resulting materials show excellent performance for photocatalytic in situ hydrogen generation. Pristine g-C₃N₄ has poor photocatalytic hydrogen evolution activity (about 1.9 μmol·h^-1) because of the rapid recombination of electron-hole pairs. However, the hydrogen generation activity is well improved after growing Ni₃Se₄ and CoSe₂ on the surface of g-C₃N₄, owing to the unique effect of these selenides in accelerating the separation and migration of charge carriers. The hydrogen production activities of G-C₃N₄@Ni₃Se₄ and g-C₃N₄@CoSe₂ are about 16.4 μmol·h^-1 and 25.6 μmol·h^-1, which are 8-fold and 13-fold that of pristine g-C₃N₄, respectively. In detail, coupling Ni₃Se₄ and CoSe₂ with g-C₃N₄ greatly improves the light absorbance density and extends the light response region. The photoluminescence intensity of the photoexcited Eosin Y dye in the presence of g-C₃N₄@Ni₃Se₄ and g-C₃N₄@CoSe₂ is weaker than that in the presence of pure g-C₃N₄. On the other hand, the upper limit of the electron-transfer rate constants in the presence of g-C₃N₄@Ni₃Se₄ and g-C₃N₄@CoSe₂ is greater than that in the presence of pure g-C₃N₄. Among the g-C₃N₄@Ni₃Se₄@FTO, g-C₃N₄@CoSe₂@FTO, and g-C₃N₄@FTO electrodes, the g-C₃N₄@FTO electrode has the lowest photocurrent density and the highest electrochemical impedance, implying that the introduction of CoSe₂ and Ni₃Se₄ onto the surface of g-C₃N₄ enhances the separation and transfer efficiency of photogenerated charge carriers. In other words, the formation of two star metals selenide based on g-C₃N₄ can efficiently inhibit the recombination of photogenerated charge carriers and accelerate photocatalytic water splitting to generate H₂. Meanwhile, the right shift of the absorption band edge effectively reduces the transition threshold of the photoexcited electrons from the valence band to the conduction band. In addition, the more negative zeta potential for the g-C₃N₄@Ni₃Se₄ and g-C₃N₄@CoSe₂ catalysts as compared with that for pure g-C₃N₄ leads to a notable enhancement in the adsorption of protons by the sample surface. Moreover, the results of density functional theory calculations indicate that the hydrogen adsorption energy of the N sites in g-C₃N₄ is -0.22 eV; further, the hydrogen atoms are preferentially adsorbed at the bridge site of two selenium atoms to form a Se―H―Se bond, and the adsorption energy is 1.53 eV. In-depth characterization has been carried out by transmission electron microscopy, scanning electron microscopy, X-ray photoelectron spectroscopy, X-ray diffraction, ultraviolet-visible diffuse reflectance spectroscopy, transient photocurrent measurements, and Fourier transform infrared spectroscopy; the results of these experiments are in good agreement with one another.

Key words: Ni₃Se₄, CoSe₂, g-C₃N₄, Hydrogen evolution

MSC2000:

O644

靳治良, 李彦兵, 郝旭强. Ni, Co基硒化物修饰g-C₃N₄光催化产氢研究[J]. 物理化学学报, 2021, 37(10): 1912033.

Zhiliang Jin, Yanbing Li, Xuqiang Hao. Ni, Co-Based Selenide Anchored g-C₃N₄ for Boosting Photocatalytic Hydrogen Evolution[J]. Acta Phys. -Chim. Sin., 2021, 37(10): 1912033.

图/表 17

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System		EY	g-C₃N₄	CN@NS-3	CN@CS-3
Lifetime, τ (ns)	τ₁	0.35	0.02	3.07	3.7
	τ₂			0.05	0.31
Rel (%)	A₁	100	100	1.87	1.41
	A₂			98.13	98.59
K_et				3.0 × 10¹⁰	4.7 × 10¹⁰
Average Lifetime (ns)		0.35	0.02	0.05	0.32
χ²		1.4	1.8	1.1	1.7

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[15]	李小为,王彬,尹文轩,狄俊,夏杰祥,朱文帅,李华明. Cu²⁺改性g-C₃N₄光催化剂的光催化性能[J]. 物理化学学报, 2020, 36(3): 1902001 - .

Ni, Co基硒化物修饰g-C₃N₄光催化产氢研究

Ni, Co-Based Selenide Anchored g-C₃N₄ for Boosting Photocatalytic Hydrogen Evolution

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Ni(CH₃COO)₂?4H₂O	Se	NaBH₄	g-C₃N₄	Sample
25	10	80	300	CN@NS-1
75	30	110	300	CN@NS-3
125	50	130	300	CN@NS-5
175	70	150	300	CN@NS-7

Sample	S_BET/(m²?g^-1)	Pore volume/(cm³?g^-1)	Average pore size/nm
Pure g-C₃N₄	44	0.10	15
CN@CS-3	25	0.12	19
CN@NS-3	23	0.10	16