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    Chinese Journal of Catalysis
    2020, Vol. 41, No. 5
    Online: 18 May 2020

    Cover: The catalyst design for oxygen reduction reaction (ORR) is one of the key technologies in fuel cell. Mao and coauthors reported a ZnCl2-facilitated calcination route for preparation of macro-/meso-porous FeNC materials with dense distribution and improved exposure of active sites (see article on pages 799–806). Zhang and coauthors found that interatomic diffusion for Pd@Pt core-shell catalysts occurs at temperatures as low as 200 ℃, by which the thermal stability of such structure has been interpreted (see article on pages 807–812).
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    Contents
    Table of Contents for VOL.41 No.5
    2020, 41 (5):  0-0. 
    Abstract ( 18 )   PDF (1226KB) ( 53 )  
    Special Column on Electrocatalysis
    Preface to Special Column on Electrocatalysis
    Zidong Wei, Minhua Shao
    2020, 41 (5):  731-731.  DOI: 10.1016/S1872-2067(20)63558-6
    Abstract ( 39 )   [Full Text(HTML)] () PDF (169KB) ( 211 )  
    Recent progress on oxygen and hydrogen peroxide reduction reactions on Pt single crystal electrodes
    Valentín Briega-Martos, Enrique Herrero, Juan M. Feliu
    2020, 41 (5):  732-738.  DOI: 10.1016/S1872-2067(19)63325-5
    Abstract ( 108 )   [Full Text(HTML)] () PDF (646KB) ( 245 )  
    Pt alloy oxygen-reduction electrocatalysts: Synthesis, structure, and property
    Xiao Xia Wang, Joshua Sokolowski, Hui Liu, Gang Wu
    2020, 41 (5):  739-755.  DOI: 10.1016/S1872-2067(19)63407-8
    Abstract ( 339 )   [Full Text(HTML)] () PDF (2215KB) ( 588 )  
    Proton exchange membrane fuel cells (PEMFCs) are considered a promising power source for electric vehicles and stationary residential applications. However, current PEMFCs have several problems that require solutions, including high cost, insufficient power density, and limited performance durability. A kinetically sluggish oxygen reduction reaction (ORR) is primarily responsible for these issues. The development of advanced Pt-based catalysts is crucial for solving these problems if the large-scale application of PEMFCs is to be realized. In this review, we summarize the recent progress in the development of PtM alloy (M=Fe, Co, Ni, etc.) catalysts with an emphasis on ordered PtM intermetallic catalysts, which exhibit significantly enhanced activity and stability. In addition to exploring the intrinsic catalytic performance in traditional aqueous electrolytes via engineering nanostructures, morphologies, and crystallinity of PtM particles, we highlight recent efforts to study catalysts under real fuel cell environments by the membrane electrode assembly (MEA).
    Electrochemical hydrogen compression and purification versus competing technologies: Part I. Pros and cons
    Maha Rhandi, Marine Trégaro, Florence Druart, Jonathan Deseure, Marian Chatenet
    2020, 41 (5):  756-769.  DOI: 10.1016/S1872-2067(19)63404-2
    Abstract ( 322 )   [Full Text(HTML)] () PDF (678KB) ( 543 )  
    It is undisputed that hydrogen will play a great role in our future energetic mix, because it enables the storage of renewable electricity (power-to-H2) and the reversible conversion into electricity in fuel cell, not to speak of its wide use in the (petro)chemical industry. Whereas in these applications, pure hydrogen is required, today's hydrogen production is still largely based on fossil fuels and can therefore not be considered pure. Therefore, purification of hydrogen is mandatory, at a large scale. In addition, hydrogen being the lightest gas, its volumetric energy content is well-below its competing fuels, unless it is compressed at high pressures (typically 70 MPa), making compression unavoidable as well. This contribution will detail the means available today for both purification and for compression of hydrogen. It will show that among the available technologies, the electrochemical hydrogen compressor (EHC), which also enables hydrogen purification, has numerous advantages compared to the classical technologies currently used at the industrial scale. EHC has their thermodynamic and operational advantages, but also their ease of use. However, the deployment of EHCs will be viable only if they reach sufficient performances, which implies some specifications that their base materials should stick to. The present contribution will detail these specifications.
    Electrochemical hydrogen compression and purification versus competing technologies: Part II. Challenges in electrocatalysis
    Marine Trégaro, Maha Rhandi, Florence Druart, Jonathan Deseure, Marian Chatenet
    2020, 41 (5):  770-782.  DOI: 10.1016/S1872-2067(19)63438-8
    Abstract ( 256 )   [Full Text(HTML)] () PDF (888KB) ( 463 )  
    Hydrogen will be at the basis of the World's energy policy in forthcoming decades, owing to its decarbonized nature, at least when produced from renewables. For now, hydrogen is still essentially produced from fossil feedstock (and to a minor extent from biomass); in consequence the present hydrogen gas on the market is containing non-negligible amounts of impurities that prevent its immediate usage in specialty chemistry or as an energy carrier in fuel cells, e.g. in transportation applications (cars, buses, trains, boats, etc.) that gradually spread on the planet. For these purposes, hydrogen must be of sufficient purity but also sufficiently compressed (at high pressures, typically 70 MPa), rendering purification and compression steps unavoidable in the hydrogen cycle. As shown in the first part of this contribution "Electrochemical hydrogen compression and purification versus competing technologies: Part I. pros and cons", electrochemical hydrogen compressors (EHCs), which enable both hydrogen purification and compression, exhibit many theoretical (thermodynamic) and practical (kinetics) advantages over their mechanical counterparts. However, in order to be competitive, EHCs must operate in very intensive conditions (high current density and low cell voltage) that can only be reached if their core materials, e.g. the membrane and the electrodes/electrocatalysts, are optimized. This contribution will particularly focus on the properties electrocatalysts must exhibit to be used in EHCs:they shall promote (very) fast hydrogen oxidation reaction (HOR) in presence of impurities, which implies that they are (very) tolerant to poisons as well. This consists of a prerequisite for the operation of the anode of an EHC used for the purification-compression of hydrogen, and the materials developed for poison-tolerance in the vast literature on low-temperature fuel cells, may not always satisfy these two criteria, as this contribution will review.
    Supported dual-atom catalysts: Preparation, characterization, and potential applications
    Jing Zhang, Qiu-an Huang, Juan Wang, Jing Wang, Jiujun Zhang, Yufeng Zhao
    2020, 41 (5):  783-798.  DOI: 10.1016/S1872-2067(20)63536-7
    Abstract ( 572 )   [Full Text(HTML)] () PDF (1984KB) ( 989 )  
    Developing sustainable and clean electrochemical energy conversion technologies is a crucial step in addressing the challenges of energy shortage and environmental pollution. Exploring and developing new electrocatalysts with excellent performance and low cost will facilitate the commercial use of these energy conversion technologies. Recently, dual-atom catalysts (DACs) have attracted considerable research interest since they exhibit higher metal atom loading and more flexible active sites compared to single-atom catalysts (SACs). In this paper, the latest preparation methods and characterization techniques of DACs are systematically reviewed. The advantages of homonuclear and heteronuclear DACs and the catalytic mechanism and identification technologies between the two DACs are highlighted. The current applications of DACs in the field of electrocatalysis are summarized. The development opportunities and challenges of DACs in the future are prospected. The ultimate goal is to provide new ideas for the preparation of new catalysts with excellent properties by customizing diatomic catalysts for electrochemical applications.
    ZnCl2 salt facilitated preparation of FeNC: Enhancing the content of active species and their exposure for highly-efficient oxygen reduction reaction
    Zhan Xin Mao, Min Jie Wang, Lu Liu, Lishan Peng, Siguo Chen, Li Li, Jing Li, Zidong Wei
    2020, 41 (5):  799-806.  DOI: 10.1016/S1872-2067(19)63405-4
    Abstract ( 176 )   [Full Text(HTML)] () PDF (719KB) ( 292 )  
    Supporting Information
    Introducing catalytically-active Fe and N into carbon materials results in promising FeNC catalysts for oxygen reduction reaction. However, the doped Fe and N species are frequently subject to heavy loss in a traditional carbonization process owing to Fe agglomeration and evaporation of N-contained small molecules. Besides, pyrolysis may make materials sintering which embeds a large number of active sites in the bulk phase and impedes direct exposure of reactive centers to the reactants. We here report that when calcinations, the addition of ZnCl2, an ordinary salt with very wide melting temperature range well covering the carbonization process of the precursor iron porphyrin, can significantly enhance the doping level of the active species and simultaneously create highly porous structures for FeNC catalysts. The obtained FeNC demonstrates ultrahigh catalytic activities even significantly better than Pt/C in oxygen reduction reaction.
    Interatomic diffusion in Pd-Pt core-shell nanoparticles
    Yanfeng Zhang, Shangqian Zhu, Lili Zhang, Dong Su, Minhua Shao
    2020, 41 (5):  807-812.  DOI: 10.1016/S1872-2067(19)63451-0
    Abstract ( 103 )   [Full Text(HTML)] () PDF (498KB) ( 266 )  
    Supporting Information
    Pt monolayer-based core-shell catalysts have garnered significant interest for the application of low temperature fuel cell technology as their use may enable a decreased loading of Pt while still providing sufficient current density to meet volumetric requirements. One promising candidate in this class of materials is a Pd@Pt core-shell catalyst, which shows enhanced activity toward oxygen reduction reaction (ORR). One concern with the use of Pd@Pt, however, is the durability of the core-shell structure as Pd atoms are thermodynamically favored to migrate to the surface. The pathway of the migration has not been systematically studied. The current study explores the stability of this structure to thermal annealing and probes the effect of this heat treatment on the catalyst surface structure and its oxygen reduction activity. It was found that surface alloying between Pd and Pt occurs at temperatures as low as 200℃, and significantly alters the structure and ORR catalytic activity in the range of 200-300℃. Our results shed lights on the thermal induced interatomic diffusion in all core-shell and thin film structures.
    Surface elemental distribution effect of Pt-Pb hexagonal nanoplates for electrocatalytic methanol oxidation reaction
    Hee Jin Kim, Yong-Deok Ahn, Jeonghyeon Kim, Kyoung-Su Kim, Yeon Uk Jeong, Jong Wook Hong, Sang-Il Choi
    2020, 41 (5):  813-819.  DOI: 10.1016/S1872-2067(19)63310-3
    Abstract ( 158 )   [Full Text(HTML)] () PDF (607KB) ( 315 )  
    Bimetallic Pt-based catalysts have been extensively investigated to enhance the performance of direct methanol fuel cells (DMFCs) because CO, a by-product, reduces the activity of the pure Pt catalysts. Herein, we synthesized Pt-Pb hexagonal nanoplates as a model catalyst for the methanol oxidation reaction (MOR) and further controlled the Pt and Pb distributions on the surface of the nanoplates through acetic acid (HAc) treatment. As a result, we obtained Pt-Pb nanoplates and HAc-treated Pt-Pb nanoplates with homogeneous and heterogeneous distributions of the Pt-Pb alloy surfaces, respectively. We showed that the MOR activity and stability of the Pt-Pb nanoplates improved compared to those of the HAc-treated Pt-Pb nanoplates, mainly due to the enhanced CO tolerance and the modified electronic structure of Pt under the influence of the oxophilic Pb.
    Investigation on the coordination mechanism of Pt-containing species and qualification of the alkaline content during Pt/C preparation via a solvothermal polyol method
    Rongrong Zeng, Kun Wang, Wei Shao, Junhang Lai, Shuqin Song, Yi Wang
    2020, 41 (5):  820-829.  DOI: 10.1016/S1872-2067(19)63456-X
    Abstract ( 1095 )   [Full Text(HTML)] () PDF (924KB) ( 594 )  
    A solvothermal assisted ethylene glycol reduction method is a common technology for Pt/C catalysts preparation. Here, the coordination mechanism of the Pt-containing species is deeply studied by innovatively adopting the ultraviolet-visible spectroscopy technology and H+ concentration detector. Moreover, the amount of NaOH that effectively coordinates Pt4+ has been tentatively qualified and the heating parameters during the preparation process of Pt/C have also been optimized. As investigated, the optimized 20-(1/22)-140-2 Pt/C (20 wt%Pt; m(Pt):m(NaOH)=1/22; heating temperature:140℃, heating time:2 h) exhibits higher electrocatalytic activity towards oxygen reduction reaction (ORR) than the commercial 20 wt% Pt/C (E-TEK) in acidic media. This work provides a theoretical reserve and technical accumulation for industrialized mass production of highly efficient Pt/C catalysts for ORR in proton exchange membrane fuel cells.
    Nitrogen and sulfur dual-doped high-surface-area hollow carbon nanospheres for efficient CO2 reduction
    Guodong Li, Yongjie Qin, Yu Wu, Lei Pei, Qi Hu, Hengpan Yang, Qianling Zhang, Jianhong Liu, Chuanxin He
    2020, 41 (5):  830-838.  DOI: 10.1016/S1872-2067(19)63485-6
    Abstract ( 110 )   [Full Text(HTML)] () PDF (736KB) ( 331 )  
    Supporting Information
    The electrochemical reduction of CO2 (CO2RR) can substantially contribute to the production of useful chemicals and reduction of global CO2 emissions. Herein, we presented N and S dual-doped high-surface-area carbon materials (SZ-HCN) as CO2RR catalysts. N and S were doped by one-step pyrolysis of a N-containing polymer and S powder. ZnCl2 was applied as a volatile porogen to prepare porous SZ-HCN. SZ-HCN with a high specific surface area (1510 m2 g-1) exhibited efficient electrocatalytic activity and selectivity for CO2RR. Electrochemical measurements demonstrated that SZ-HCN showed excellent catalytic performance for CO2-to-CO reduction with a high CO Faradaic efficiency (~93%) at -0.6 V. Furthermore, SZ-HCN offered a stable current density and high CO selectivity over at least 20 h continuous operation, revealing remarkable electrocatalytic durability. The experimental results and density functional theory calculations indicated that N and S dual-doped carbon materials required lower Gibbs free energy to form the COOH* intermediate than that for single-N-doped carbon for CO2-to-CO reduction, thereby enhancing CO2RR activity.
    Robust MOF-253-derived N-doped carbon confinement of Pt single nanocrystal electrocatalysts for oxygen evolution reaction
    Hellen Gabriela Rivera Monestel, Ibrahim Saana Amiinu, Andrés Alvarado González, Zonghua Pu, BibiMaryam Mousavi, Shichun Mu
    2020, 41 (5):  839-846.  DOI: 10.1016/S1872-2067(19)63488-1
    Abstract ( 160 )   [Full Text(HTML)] () PDF (710KB) ( 331 )  
    Supporting Information
    Although carbon-supported platinum (Pt/C) is still considered the most active electrocatalyst for hydrogen evolution reaction (HER) and oxygen reduction reaction (ORR), its applications in metal-air batteries as a cathode catalyst, or for oxygen generation via water splitting electrolysis as an anode catalyst is mainly constrained by the insufficient kinetic activity and stability in the oxygen evolution reaction (OER). Here, MOF-253-derived nitrogen-doped carbon (N/C)-confined Pt single nanocrystals (Pt@N/C) have been synthesized and shown to be efficient catalysts for the OER. Even with low Pt mass loading of 6.1 wt% (Pt@N/C-10), the catalyst exhibits greatly improved activity and long-time stability as an efficient OER catalyst. Such high catalytic performance is attributed to the core-shell structure relationship, in which the active N-doped-C shell not only provides a protective shield to avoid rapid Pt nanocrystal oxidation at high potentials and inhibits the Pt migration and agglomeration, but also improves the conductivity and charge transfer kinetics.
    Tuning the oxygen evolution electrocatalysis on NiFe-layered double hydroxides via sulfur doping
    Shenzhou Li, Jianyun Liu, Shuo Duan, Tanyuan Wang, Qing Li
    2020, 41 (5):  847-852.  DOI: 10.1016/S1872-2067(19)63356-5
    Abstract ( 285 )   [Full Text(HTML)] () PDF (744KB) ( 463 )  
    Supporting Information
    We report a facile way to prepare sulfur (S) doped Ni4/5Fe1/5-layered double hydroxide (LDH) electrocatalysts for oxygen evolution reaction (OER). The influence of S doping amount on the OER activity of the resulted NiFe-LDHs was studied and the optimal surface S content was ca. 0.43 at%. The developed S-doped NiFe-LDH exhibits excellent OER catalyst activity in 1.0 M KOH with overpotential of only 257 mV at the current density of 10 mA cm-2. Moreover, the catalyst could maintain high activity after 30 h stability test. The high activity of the S-doped NiFe-LDH catalysts may originate from the synergistic effect between S and the Fe sites. This work provides a simple but efficient way to improve the OER performance of transition metal oxides/(oxy)hydroxides.
    Communication
    Fe-substituted cobalt-phosphate polyoxometalates as enhanced oxygen evolution catalysts in acidic media
    Xin-Bao Han, Dong-Xue Wang, Eduardo Gracia-Espino, Yu-Hui Luo, Yuan-Zhi Tan, Dong-Fei Lu, Yang-Guang Li, Thomas W?gberg, En-Bo Wang, Lan-Sun Zheng
    2020, 41 (5):  853-857.  DOI: 10.1016/S1872-2067(20)63538-0
    Abstract ( 166 )   [Full Text(HTML)] () PDF (594KB) ( 380 )  
    Supporting Information
    All-inorganic and earth-abundant bi-/trimetallic hydr(oxy)oxides are widely used as oxygen evolution electrocatalysts owing to their remarkable performance. However, their atomically precise structures remain undefined, complicating their optimization and limiting the understanding of their enhanced performance. Here, the underlying structure-property correlation is explored by using a well-defined cobalt-phosphate polyoxometalate cluster[{Co4(OH)3(PO4)}4(SiW9O34)4]32- (1), which may serve as a molecular model of multimetal hydr(oxy)oxides. The catalytic activity is enhanced upon replacing Co by Fe in 1, resulting in a reduced overpotential (385 mV) for oxygen evolution (by 66 mV) compared to that of the parent 1 at 10 mA cm-2 in an acidic medium; this overpotential is comparable to that for the IrO2 catalyst. These abundant-metal-based polyoxometalates exhibit high stability, with no evidence of degradation even after 24 h of operation.
    Articles
    Iron-incorporated nitrogen-doped carbon materials as oxygen reduction electrocatalysts for zinc-air batteries
    Kai Chen, Suqin Ci, Qiuhua Xu, Pingwei Cai, Meizhen Li, Lijuan Xiang, Xi Hu, Zhenhai Wen
    2020, 41 (5):  858-867.  DOI: 10.1016/S1872-2067(19)63507-2
    Abstract ( 137 )   [Full Text(HTML)] () PDF (882KB) ( 356 )  
    Supporting Information
    The application of electrocatalysts for the oxygen reduction reaction (ORR) is vital in a variety of energy conversion technologies. Exploring low-cost ORR catalysts with high activity and long-term stability is highly desirable, although it still remains challenging. Herein, we report a facile and reliable route to convert ZIF-8 modified by Fe-phenanthroline into Fe-incorporated and N-doped carbon dodecahedron nanoarchitecture (Fe-NCDNA), in which carbon nanosheets are formed in situ as the building blocks with uniform Fe-N-C species decoration. Systematic electrochemical studies demonstrate that the as-synthesized Fe-NCDNA electrocatalyst possesses highly attractive catalytic features toward the ORR in terms of activity and durability in both alkaline and neutral media. The Zn-air battery with the optimal Fe-NCDNA catalyst as the cathode performs impressively, delivering a power density of 184 mW cm-2 and a specific capacity of 801 mAh g-1; thus, it exhibits great competitive advantages over those of the Zn-air devices employing a Pt-based cathode electrocatalyst.
    Special Column on Electrocatalysis
    Green aerobic oxidative desulfurization of diesel by constructing an Fe-Anderson type polyoxometalate and benzene sulfonic acid-based deep eutectic solvent biomimetic cycle
    Jiajia Xu, Zhiguo Zhu, Ting Su, Weiping Liao, Changliang Deng, Dongmei Hao, Yuchao Zhao, Wanzhong Ren, Hongying Lü
    2020, 41 (5):  868-876.  DOI: 10.1016/S1872-2067(19)63500-X
    Abstract ( 91 )   [Full Text(HTML)] () PDF (606KB) ( 342 )  
    A unique redox-coupled biomimetic system was developed, in which Fe-Anderson type polyoxometalates (POMs) were employed as electron transfer mediators (ETMs) and benzenesulfonic acid (BSA)-based deep eutectic solvents (DESs) were used as electron-donors for aerobic oxidative desulfurization (AODS) of diesel fuel. Different compositions of DESs were used and the polyethylene glycol 2000 (PEG2000)/2.5BSA system showed the highest desulfurization activity, with the removal of dibenzothiophene (DBT) at 60℃ reaching 95% in 60 min. The excellent desulfurization activity of the system is due to the in situ formation of peroxysulfonate via a biomimetic process. By constructing a coupled redox system, Fe-Anderson type POMs as ETMs reduce the activation energy of oxygen-activated sulfonate. The physical characteristics of four different DESs were tested. The results show that the conductivity of DESs is correlated with the composition of BSA-based DESs. However, there is no similar trend in viscosity testing at the same temperature, and the maximum viscosity value is obtained for the PEG2000/2.5BSA system at 60℃, which may be associated with the stronger hydrogen bonds. It is worth noting that the PEG2000/2.5BSA system also possesses the best desulfurization activity, which suggests that the activity of the desulfurization system is related to the strength of the hydrogen bond in DESs. Finally, the biomimetic desulfurization system exhibits excellent performance and good stability under mild reaction conditions (60℃, atmospheric pressure, oxygen as the oxidant).
    Articles
    Investigation of lattice capacity effect on Cu2+-doped SnO2 solid solution catalysts to promote reaction performance toward NOx-SCR with NH3
    Xianglan Xu, Yunyan Tong, Jingyan Zhang, Xiuzhong Fang, Junwei Xu, Fuyan Liu, Jianjun Liu, Wei Zhong, Olga E. Lebedeva, Xiang Wang
    2020, 41 (5):  877-888.  DOI: 10.1016/S1872-2067(20)63532-X
    Abstract ( 49 )   [Full Text(HTML)] () PDF (778KB) ( 225 )  
    Supporting Information
    To understand the effect of the doping amount of Cu2+ on the structure and reactivity of SnO2 in NOx-SCR with NH3, a series of Sn-Cu-O binary oxide catalysts with different Sn/Cu ratios have been prepared and thoroughly characterized. Using the XRD extrapolation method, the SnO2 lattice capacity for Cu2+ cations is determined at 0.10 g CuO per g of SnO2, equaling a Sn/Cu molar ratio of 84/16. Therefore, in a tetragonal rutile SnO2 lattice, only a maximum of 16% of the Sn4+ cations can be replaced by Cu2+ to form a stable solid solution structure. If the Cu content is higher, CuO will form on the catalyst surface, which has a negative effect on the reaction performance. For samples in a pure solid solution phase, the number of surface defects increase with increasing Cu content until it reaches the lattice capacity, as confirmed by Raman spectroscopy. As a result, the amounts of both active oxygen species and acidic sites on the surface, which critically determine the reaction performance, also increase and reach the maximum level for the catalyst with a Cu content close to the lattice capacity. A distinct lattice capacity threshold effect on the structure and reactivity of Sn-Cu binary oxide catalysts has been observed. A Sn-Cu catalyst with the best reaction performance can be obtained by doping the SnO2 matrix with the lattice capacity amount of Cu2+.
    Controllable photochemical synthesis of amorphous Ni(OH)2 as hydrogen production cocatalyst using inorganic phosphorous acid as sacrificial agent
    Dandan Li, Yuming Dong, Guangli Wang, Pingping Jiang, Feiyan Zhang, Huizhen Zhang, Ji Li, Jinze Lyu, Yan Wang, Qingyun Liu
    2020, 41 (5):  889-897.  DOI: 10.1016/S1872-2067(19)63499-6
    Abstract ( 120 )   [Full Text(HTML)] () PDF (922KB) ( 258 )  
    Supporting Information
    Loading of cocatalysts can effectively inhibit the recombination of photogenerated carriers in photocatalysts and greatly improve the photocatalytic hydrogen production rate. Cocatalysts can be deposited at the outlet points of electrons using a photochemical method, which is beneficial for the following photocatalytic hydrogen production reaction. H2PO2- has been used in the photochemical reduction of transition metals because of its special properties. However, the particles formed in the presence of H2PO2- are very large and highly crystalline, which may inhibit the activity of photocatalysts. In this study, we designed a new method for synthesizing photocatalysts by photodeposition using some other phosphates, aiming to prepare controllable weakly crystalline and small-size cocatalysts to improve the hydrogen production activity. The cocatalyst prepared using H2PO3- as an inorganic sacrificial agent has an amorphous structure and an average size of about 10 nm. The optimal photocatalytic hydrogen production rate of the obtained Ni(OH)2/g-C3N4 (4.36 wt%) is 13707.86 μmol·g-1·h-1, which is even higher than the activity of Pt-4.36 wt%/g-C3N4 (11210.93 μmol·g-1·h-1). Mechanistic studies show that loading of Ni(OH)2 can efficiently accelerate the separation and transfer efficiency of photogenerated charge carriers.