Low Platinum Content Research Articles

Engineering medium-entropy alloy nanoparticle nanotubes for efficient oxygen reduction

Fuel cells, as promising energy conversion devices, realize the direct conversion of hydrogen fuel chemical energy into electrical energy. The kinetics of cathodic oxygen reduction reaction (ORR) is slow and plays a decisive role in the output efficiency of fuel cells. Platinum catalysts have been commercialized, but their high cost, relatively low catalytic activity and poor cycling durability limit the development of fuel cells. The introduction of non-platinum components is an effective strategy to minimize the cost and maximize the activity. In this study, PtPdCu medium entropy alloy nanoparticle nanotubes (PtPdCu MEANPTs) that demonstrate high catalytic activity and long durability are presented. Combined with density functional theory calculations, the introduction of Pd and Cu modulates surface electronic structure and optimizes the oxygen adsorption energy, thus enhancing the catalytic activity. The 0D/1D hybrid structure exposes more surface sites and inhibits particle maturation. The atomic migration and rearrangement are emerged during the initial stage of potential cycling process, induing a palladium-rich outer layer and preventing the oxidation of platinum atoms. The best-performing Pt24Pd28Cu48 MEANPTs deliver the impressive ORR activity (1.42 A/mgPt at 0.9 V vs. RHE, which is 6.17 times that of commercial Pt/C) and durability (retaining 2.87 times the initial activity of benchmark catalyst after 30,000 potential cycles). Theoretical calculations have confirmed the regulation of alloying on the surface oxygen affinity and revealed the true active sites on the catalyst surface. This work explores the research direction of platinum-based multi-element catalysts with low platinum content and high catalytic activity.

Hydrogen Evolution Activity of Platinum Nanoparticles Decorated on Silver Nanowire Networks and Graphite Electrodes

The catalytic activity of graphite (C) and conductive silver nanowire (AgNW) networks coated on glass and graphite substrates with low platinum content towards hydrogen evolution reaction (HER) is reported. The results exhibit that the chronoamperometric electrodeposition of platinum on AgNW substrates results in the formation of spherically shaped nanoparticle agglomerates aligned on the nanowires. Also, platinum doped graphite electrodes with a rough surface showed an efficient distribution of platinum nanoparticles (PtNPs). Studies of the electrocatalytic HER activity as a function of platinum loading indicate that the optimum loading is in the range of 60 µg/cm2 and further loading results only in a minor reduction of the overpotential. At low Pt content, a synergistic effect of the AgNW network in terms of enhancement of the HER performance was observed. Tafel analysis showed that in the low overpotential region, the Volmer reaction was the rate determining step for the graphite based electrodes. The graphite substrate in conductive connection with the nanowires was shown to significantly boost the hydrogen formation rate.

Be aware of the effect of electrode activation and morphology on its performance in gas diffusion electrode setups

The superior performance enhancement in catalyst research for proton exchange membrane fuel cells (PEMFC) revealed in the model rotating disc electrode (RDE) environment is rarely demonstrated in membrane electrode assemblies (MEA). The discrepancy is typically attributed to the difference in the chemical structure and morphology of the catalyst layer (CL), affecting the transport of reactants of the oxygen reduction reaction (ORR). In this study, the gas diffusion electrode (GDE) half-cell setup is used to focus on crucial aspects of CL development, especially on the activation and morphology of CLs, to gain a fundamental understanding of the development of PEMFCs. Adjusting the CL porosity by using different solvent compositions of water and isopropyl alcohol and implementing an activation method for low platinum content catalysts, we focus on understanding the contributions of macro-porosity and hydrophobicity in a liquid electrolyte-based system. We show that macro-porosity significantly influences the O2 mass transport in the CL, demonstrating increased performance with higher porosities. Coupling inductively coupled plasma mass spectrometry (ICP-MS) with the GDE half-cell setup, we propose a method for qualitative estimation of water content in the CL. Lower macro-porosity shows higher platinum dissolution, attributed to improved mass transport of dissolved ions in aqueous media.

Low-Platinum-Content Exchange-Coupled CoPt Nanoalloys with Enhanced Magnetic Properties.

Bimetallic colloidal CoPt nanoalloys with low platinum content were successfully synthesized following a modified polyol approach. Powder X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), thermogravimetric analysis (TGA), and transmission electron microscopy (TEM) studies were performed to estimate the crystal structure, morphology, and surface functionalization of the colloids, respectively, while the room-temperature magnetic properties were measured using a vibrating sample magnetometer (VSM). The particles exhibit excellent uniformity, with a narrow size distribution, and display strong room-temperature hysteretic ferromagnetic behavior even in the as-made form. Upon annealing at elevated temperatures, progressive formation and co-existence of exchange coupled, of both chemically ordered and disordered phases significantly enhanced the room-temperature coercivity.

Testing of Electromigration Resistance of Copper and Silver Thick Films

This paper is focused on the electromigration resistance of copper and silver thick films. Electromigration was tested by water drop test. Four common conductive thick film pastes were used for testing – silver paste with low platinum content, and two silver pastes with different content of palladium and copper paste. Electromigration was tested under voltage of 6 and 12 V and time to shortcut was measured. Results of testing including the comparison of electromigration resistance depending on thick film paste type and different electrode spacing are described in this paper.

(Keynote) Experimental and Computational Insights into Electronic Structure and Redox Properties of Bare and Doped Co3O4 Nanocrystals of Euhedral Morphology and Their Heterojunctions with Alien Oxides and Carbon Materials

One of the most attractive oxide materials with remarkable record of widespread applications are cobalt spinels and their derivatives obtained by doping with alien redox (3dn) and nonredox (Li) cations or via hybridization with other oxides (CeO2, TiO2, a-Al2O3) or carbon support. They have recently received a great deal of theoretical and practical attention because of an outstanding activity in many redox processes important for photo/electro/catalysis. Among many potential applications, their relevance as promising substitutes for platinum in oxygen reduction reaction (ORR) or oxygen evolution reaction (OER) can be mentioned, in particular. The properties of nanostructured cobalt spinel materials depend on their size, shape, doping and interfacing features. In this context, euhedral spinel nanocrystals that expose well defined crystallographic planes, allow for sensible investigations into establishment of the surface/bulk structure-redox reactivity relationships in real conditions.In this presentation application of S/TEM and inverse Wulff hull matching techniques supported by image simulation was discussed for elucidation the mechanism of hydrothermal synthesis of euhedral cobalt spinel nanocrystals the their shape retrieving. Periodic spin unrestricted DFT-PW91+U and hybrid DFT/HSE06 calculations were applied for modeling the morphology, structure and electronic properties (DOS structure) relevant for redox behavior of bare and doped cobalt spinel nanocrystals. The results allowed for thorough characterization of the structure and reconstruction of the exposed low index (100), (110), and (111) planes, and explain the influence of dopants. The effect of the valence state of lithium (Li+ or Li0), and its locus on the valence pining of the cobalt cations was determined. DFT calculations together with the ab initio thermodynamic modeling were used to study the electronic structure of the created defects, and stability of different terminations of cobalt spinel and Li-doped Co3O4 under various redox conditions. The associated electronic and spin relaxation processes were discussed as well. For the most stable stoichiometric (100) and (111) facets, the surface redox state diagrams in a wide stoichiometry range were constructed, and analyzed in detail. Intrinsic charge transfer processes involving electron (n-conductivity) and hole (p-conductivity) transfer between the octahedral and tetrahedral cobalt cations were modeled using a small polaron approximation (Marcus-Dupuis model). Formation of n-p junctions (Co3O4|CeO2, Li-Co3O4|CeO2) and MxCo3-xO4/carbon hybrids were analyzed by S/TEM, XPS spectroscopy (band alignment), contactless electronic conductivity and work function measurements, corroborated by DFT modeling. The redox properties of the interface and spinel faceting, and the role of electric conductivity and the nature of the carbon support functional groups were discussed in the context of the ORR, OER performance, and catalytic redox reactivity (activation of O2).AcknowledgmentsS.W. thanks for the financial support of the project “High-performance electrocatalyst for oxygen reduction reaction with low platinum content” carried on within the Program “Pearls of Science” of the Ministry of Education and Science of Poland.

Electrochemical Surface-Enhanced Raman Spectroscopy (EC-SERS) Study of C3 Polyalcohols Oxidation Catalyzed by a Ag Roughened Electrode with Low Platinum Content

Electrochemical Surface-Enhanced Raman Spectroscopy (EC-SERS) Study of C3 Polyalcohols Oxidation Catalyzed by a Ag Roughened Electrode with Low Platinum Content

Facile Synthesis of Nitrogen Doped Porous Carbon Supported Platinum Catalyst and Improvement of Electrocatalytic Ethanol Performance

Direct ethanol fuel cells (DEFCs) have become an alternative to traditional fossil fuels because of their low emissions, fast start-up and high energy density. Platinum (Pt)-based catalysts are the most effective catalysts for DEFCs, but their high cost and poor electrocatalytic performance hinder their practical application. Therefore, there is an urgent need to design Pt-based catalysts with low platinum content, high electrochemical activity and stability. Herein, nitrogen-doped porous carbon-loaded Pt catalysts (Pt@Co-CN) were prepared by in situ polymerization and high-temperature calcination using the metal-organic framework materials (MOFs) ZIF-8@ZIF-67 as the carriers. The effects of the addition of pyrrole monomer on the morphology and electrocatalytic properties of the samples were investigated. The sample with the complete coating layer and uniformly dispersed Pt nanoparticles (Pt@Co-CN) could be obtained by adding an appropriate amount of pyrrole monomer. The results of the electrochemical tests showed that the electrochemical activity of Pt@Co-CN catalytic ethanol is superior to that of commercial catalysts and samples with insufficient or excessive addition of pyrrole monomers. The content of this study provides a new method for the electrocatalyst of DEFCs.

Highly Efficient Electrochemical Hydrogen Evolution with Ultra-Low Loading of Strongly Adhered Pt Nanoparticles on Carbon.

The development of robust electrocatalysts with low platinum content for acidic hydrogen evolution reaction (HER) is paramount for large scale commercialization of proton exchange membrane electrolyzers. Herein, a simple strategy is reported to synthesize a well anchored, low Pt containing Vulcan carbon catalyst using ZnO as a sacrificial template. Pt containing ZnO (PZ) is prepared by a simultaneous borohydride reduction. PZ is then loaded onto Vulcan carbon to produce a very low Pt content electrocatalyst, PZ@VC. PZ@VC with 2wt.% Pt shows excellent performance for acidic HER in comparison to the commercial Pt/C (20wt.%) catalyst. PZ@VC with a very low Pt loading shows significantly low η10 and η100 values (15 and 46mV, respectively). PZ@VC on coating with Nafion (PZ@VC-N) shows further improvement in its performance (η10 of 7mV, η100 of 28mV) with ≈300h of stability (≈10mA cm-2 ) with only 4 µgPt cm-2 . PZ@VC-N shows a record high mass activity of 71 A mgPt -1 (32 times larger than Pt/C (20 wt.%) at 50mV of overpotential. Post reaction characterizations reveal Pt nanoparticles are embedded onto VC with no traces of zinc, suggestive of a strong metal-support interaction leading to this high stability at low Pt loading.

Dislocation Network‐Boosted PtNi Nanocatalysts Welded on Nickel Foam for Efficient and Durable Hydrogen Evolution at Ultrahigh Current Densities

AbstractLarge‐scale application of alkaline water electrolysis for high‐rate hydrogen production is severely hindered by high electricity cost, mainly due to difficulties to acquire cost‐effective catalytic electrodes with both extremely low overpotential and long‐term durability at ultrahigh current densities (≥1 A cm−2). Here it is demonstrated that by adopting a synthetic method of laser direct writing in liquid nitrogen via a commercial laser welding machine, a remarkably efficient and durable electrode with large area and low platinum content is obtained, where PtNi nanocatalysts with dislocation network are firmly welded on a nickel foam (NF). The dense dislocation network not only improves intrinsic activity of a majority of surface‐active sites induced by coupled compressive‐tensile strains synergistically promoting both Volmer and Tafel steps of alkaline hydrogen evolution reaction (HER), but also well stabilizes surface dislocations for HER at ultrahigh current densities. Such a robust electrode achieves record‐low overpotentials of 5 and 63 mV at 10 and 1000 mA cm−2 in alkaline medium, respectively, exhibiting negligible activity decay after 300 h chronoamperometric test at 1 A cm−2. It displays a high Pt mass activity 16 times higher than 20 wt% Pt/C loaded on NF, surpassing most of the recently reported efficient Pt‐based catalysts.

Designing fuel cell catalyst support for superior catalytic activity and low mass-transport resistance

The development of low-Platinum content polymer electrolyte fuel cells (PEFCs) has been hindered by inexplicable reduction of oxygen reduction reaction (ORR) activity and unexpected O2 mass transport resistance when catalysts have been interfaced with ionomer in a cathode catalyst layer. In this study, we introduce a bottom-up designed spherical carbon support with intrinsic Nitrogen-doping that permits uniform dispersion of Pt catalyst, which reproducibly exhibits high ORR mass activity of 638 ± 68 mA mgPt−1 at 0.9 V and 100% relative humidity (RH) in a membrane electrode assembly. The uniformly distributed Nitrogen-functional surface groups on the carbon support surface promote high ionomer coverage directly evidenced by high-resolution electron microscopy and nearly humidity-independent double layer capacitance. The hydrophilic nature of the carbon surface appears to ensure high activity and performance for operation over a broad range of RH. The paradigm challenging large carbon support (~135 nm) combined with favourable ionomer film structure, hypothesized recently to arise from the interactions of an ionic moiety of the ionomer and Nitrogen-functional group of the catalyst support, results in an unprecedented low local oxygen transport resistance (5.0 s cm−1) for ultra-low Pt loading (34 ± 2 μgPt cm−2) catalyst layer.

Effect of the PtCu/C electrocatalysts initial composition on their activity in the de-alloyed state in the oxygen reduction reaction

The promising ORR electrocatalysts with the low platinum content have been obtained by a simple method in one pot. The morphology of Pt-based nanoparticles supported on carbon was controlled to enhance the catalytic performance in oxygen reduction reaction (ORR). A detailed study of the microstructural characteristics and electrochemical behavior of the de-alloyed electrocatalysts made it possible to obtain a correlation between the effect of PtCu/C materials initial composition and their ORR activity. It has been established that the initial content of the alloying component has a significant effect on the structural reorganization of bimetallic nanoparticles. Electrochemical study results showed that the ORR performance of de-alloyed PtCu/C catalyst with large Cu content in the initial structure was better than that of de-alloyed PtCu/C catalysts with low Cu content due to the morphology advantages. A successful reorganization of NPs structure increased the ORR activity of the de-alloyed catalysts by two times. A presented approach can be applied to design of different ORR electrocatalysts based on the PtM nanoparticles.

Methodology of the PEM FC Gas Diffusion Layer Permeability Determination and Its Description Related to the Fuel Cell Flow Field Design

Hydrogen fuel cells represent an important part of the new energy scheme for low emission society. Development of the more efficient, durable and energy dense systems requires precise information on the numerous aspects, especially on the local distribution of physio-chemical quantities inside the fuel cells stacks. It is extremely difficult to obtain such information experimentally. Therefore, the mathematical modelling represents a feasible alternative. It offers an efficient and versatile way for the acquisition of required information. Accuracy of mathematical model, however, is primarily determined by the accuracy and reliability of the experimental data available. In this particular case, permeability of gas diffusion layer for reactants and products is of interest. Permeability values in porous environment are available experimentally. It is, however, important to keep in mind that permeability value is strongly dependent on the material porosity and thus on a degree of its compression inside the stack. Therefore, permeability value is varying with position over the electrode. Suitable approach, making possible to describe smoothly variation of the gas diffusion layer permeability with degree of its compression, is desirable. Traditional approach is to use corresponding semi-empirical equations. It is a purpose of this work to verify applicability of the Kozeny-Carman equation for this particular case and thus to fill in this gap in the current knowledge.Prior the experimental validation of the Kozeny-Carman equation accuracy, methodology of obtaining sufficiently accurate permeability data needs to be developed. In the first step of this process, permeability cells were designed, characterized by the homogeneous gas flow distribution in the channel, used for positioning of the gas diffusion layer sample, to be characterized. A special attention was paid to the absence of any turbulence domains close to the pressure reading ports, which could cause potential error in the observed pressure values. The figure provided documents results of the cell geometry optimization. Mathematical model calculated gas stream lines shown document fulfilling above stated conditions and thus ensuring reliability of the experimental data obtained. The cell lid determined the channel height itself. A series of lids was produced, allowing study of gas diffusion layers permeability at the different degrees of compression, i.e. porosities. The channel depth accuracy was required to be within tolerance of 2 mm. Pressure drop on the channel was determined by varying the streaming gas flow rate. Hydrogen and nitrogen (simulating air) were used as a test gasses. Permeability of gas diffusion layers were determined based on pressure drops using Darcy’s law. This set of data allowed comparing experimental data with Kozeny-Carman equation behavior. The agreement obtained was sufficient to justify the usage of this type of semi-empirical equation for the flow field mathematical modelling. Corresponding conclusion was in the last step of the study verified by means of the model serpentine flow field attached at the gas diffusion layer at the different degrees of compression. Experimental data obtained have shown very good agreement with the model calculations. It can thus be concluded, that Kozeny-Carman provides sufficient approximation of the gas diffusion permeability values to be used in the mathematical models for design of fuel cells and fuel cells stacks for geometry optimization.The work was supported from European Regional Development Fund-Project "Fuel Cells with Low Platinum Content" (No. CZ.02.1.01/0.0/0.0/16_025/0007414). Figure 1

Gas Diffusion Layer: The Critical Player in Gases Distribution in the Proton Exchange Membrane Fuel Cell

Within the last decades, fuel cells have become the center of attention of research community, industry, and the general public. This is due to the emphasis on the sustainability of the society and the emerging concept of a hydrogen economy. Proton exchange membrane fuel cells (PEM FCs) represent a mature and established fuel cell technology. The flexibility of operation, the high degree of fuel utilization, and the output power density make them suitable for mobile applications such as hydrogen-fueled vehicles or on-site energy generation. Membrane electrode assembly (MEA) is the mainstay of the PEM FCs. The MEA consists of the proton exchange membrane, catalytic layers, and gas diffusion layers (GDLs). Single MEAs are interconnected by bipolar plates with flow field channels homogenously distributing reactants and realizing easy removal of the generated water. Individual cells are compressed together, forming the fuel cell stack. The GDL plays a three-fold role in the performance of PEM fuel cells. It has to offer good electrical conductivity, ensure good reactant distribution along the reaction zone, and facilitate the removal of the water produced by the fuel cell operation. The optimal combination of these three aspects of GDL allows the FC to achieve high performance. Furthermore, the homogeneous distribution of the reactants is crucial for the durability and lifespan of the FC. The inhomogeneous reactants distribution leads to a local starvation of the electrode, leading to high local overvoltage and thus shortening the lifespan of overloaded parts. Although GDLs play a crucial role in the operation of PEM fuel cells, so far, they have received little attention. Hence, the objective of our study is to compare commercially available GDLs with respect to their properties, namely permeability under conditions close to the operating fuel cell.The approach of combining advanced mathematical modeling with extensive experimental characterization was used to achieve this task. Testing cells allowing precise determination of the in-plane permeability of various GDLs were designed based on the computational fluid dynamics modeling. According to the contemporary literature, two different carbon based GDLs were examined, namely carbon-cloth and carbon-paper, which principally differ in the carbon-fiber orientation in their internal structure. The investigated properties of GDLs thus include thickness, porosity, internal structure, and the presence or absence of microporous layer.The achieved experimental results show that at given compression, thicker carbon paper GDLs are superior to carbon cloth samples in terms of permeability and deformation resistance. The obtained permeability values of GLDs at different degrees of compression were compared with predictions based on the Carman-Kozeny equation to assess the accuracy of this semi-empirical prediction. Finally, the importance of the optimal flow field and GDL combination in terms of reactant distribution in the fuel cell stack of industrial conditions is documented via mathematical modelling based on the obtained experimental data.This work was supported by the European Regional Development Fund-Project “Fuel Cells with Low Platinum Content” (No. CZ.02.1.01/0.0/0.0/16_025/0007414).

Highly efficient hydrogen production under visible light over g-C3N4-based photocatalysts with low platinum content

The successive combination including thermolysis of melamine cyanurate complex, chemisorption of platinum from the solution of the labile nitratocomplex and, finally, reductive treatment with hydrogen was implemented to obtain highly active Pt/g-C3N4 photocatalysts (0.01–0.5 wt% of Pt). The prepared in this way materials evinces photocatalytic activity in hydrogen evolution reaction from TEOA/water solutions with the superb rate of H2 evolution per platinum atom loaded (1560 h−1) and the net rates being among the highest reported to date values (11 mmol·g−1·h−1). Such a remarkable performance correlates with the structure of these materials where the branchy net of the pores provides easy access of reagents to and ejection of products from the nanoparticulated Pt co-catalysts. A crucial contribution to the formation of the noted Pt/g-C3N4 morphology ascribed to the self-catalyzed hydrogenation of the Pt/g-C3N4 composites resulting in “scarifying” of the g-C3N4 particles preferentially at the surface layer where Pt species are located. Taking into account the high productivity of the synthesized Pt/C3N4 materials and robustness of the preparation method this approach can be convenient for the large-scale applications that were successfully demonstrated under pilot installation (total volume 1 l) with the fuel cell (PEMFC with max output 1 W) as a hydrogen consumer. Evaluation of the productivity of the large-scale reactor for hydrogen production with a scaled-up installation was carried out. This study also grants a new vision on developing expandable synthetic approaches to enhance the performance of carbon nitride-based photocatalysts and at the same time mitigate the noble metal co-catalysts usage.

Fabricating Pt/CeO2/N–C ternary ORR electrocatalysts with extremely low platinum content and excellent performance

Fabricating Pt/CeO2/N–C ternary ORR electrocatalysts with extremely low platinum content and excellent performance

Synergistic catalysis of PtM alloys and nickel hydroxide on highly enhanced electrocatalytic activity and durability for methanol oxidation reaction

The design of highly effective electrocatalysts with low platinum content for methanol oxidation reaction (MOR) is critical to develop and propel direct methanol fuel cell (DMFC) technology. Herein, we present a new co-catalysis structure tuning strategy of doping PtM (M=Cu, Co, Fe) alloys and transition metal hydroxides onto nitrogen-doped graphene to construct PtM/Ni(OH) 2 /NGO ternary hybrid electrocatalysts possessing excellent electrocatalytic performance towards efficient MOR. The unique dendritic PtM alloys and nickel hydroxide nanostructures synergistically contribute to catalyzing the oxidation of methanol and highly promoting the anti-CO poisoning ability by removal of carbonaceous intermediates on platinum active sites. The optimal hybrid catalyst achieves the higher mass and specific activity of 2883.75 mA mg Pt −1 and 6.82 mA cm −2 , respectively, and enhanced operational durability in alkaline solution. ● The unique PtM/Ni(OH) 2 /NGO catalysts have been successfully synthesized. ● Dendritic PtM alloys and Ni(OH) 2 synergistically catalyze methanol oxidation. ● PtM/Ni(OH) 2 /NGO exhibits superior MOR activity and durability. ● The anti-CO poisoning ability of the designed catalysts has been greatly enhanced.

Engineering intermetallic-metal oxide interface with low platinum loading for efficient methanol electrooxidation

Constructing a distinctive electrochemical interface with low platinum content to boost the sluggish methanol electrooxidation kinetics is critical for commercializing the direct methanol fuel cells. Herein, we have synthesized highly active electrocatalysts with unique intermetallic-metal oxide interfaces through a facile pyrolysis method. Physical characterizations demonstrate that the obtained PtFe(1:2)@a-FeOx/NC-C catalyst with low platinum content of 7.2 wt% possesses an interfacial structure composed of face-centered tetragonal (L10) PtFe intermetallic nanoparticles accompanied with amorphous iron oxide. Electrochemical measurements show that the synthesized PtFe(1:2)@a-FeOx/NC-C catalyst not only exhibits excellent methanol electrooxidation activities with a mass activity of 1.48 A mg-1Pt and a specific activity of 2.34 mA cm-2Pt in acid medium, but also possesses better CO-tolerant performance and faster methanol oxidation kinetics compared with commercial Pt/C. The improved electrochemical performances may ascribe to the modified electronic structure by alloying platinum with iron and the special PtFe@a-FeOx interface, which render strong synergistic interactions between bimetallic PtFe nanoparticles and amorphous iron oxide. Consequently, the presented strategy offers new prospects into the construction of low-cost electrocatalysts with unique electrochemical interface for enhancing catalytic performances.

Solar‐Driven H2 Generation: Solar‐Driven Hydrogen Generation Catalyzed by g‐C3N4 with Poly(platinaynes) as Efficient Electron Donor at Low Platinum Content (Adv. Sci. 4/2021)

In article number 2002465, Wai-Yeung Wong, Jun Song, and co-workers develop poly(platinaynes) as an efficient donor for g-C3N4 to form a bulk heterojunction photocatalyst for H2 production. The low-cost solution-processed poly(platinaynes) with only a small content of Pt can promote hydrogen evolution by rational skeleton modification.

Solar-Driven Hydrogen Generation Catalyzed by g-C3N4 with Poly(platinaynes) as Efficient Electron Donor at Low Platinum Content.

A metal‐complex‐modified graphitic carbon nitride (g‐C3N4) bulk heterostructure is presented here as a promising alternative to high‐cost noble metals as artificial photocatalysts. Theoretical and experimental studies of the spectral and physicochemical properties of three structurally similar molecules Fo–D, Pt–D, and Pt–P confirm that the Pt(II) acetylide group effectively expands the electron delocalization and adjusts the molecular orbital levels to form a relatively narrow bandgap. Using these molecules, the donor–acceptor assemblies Fo–D@CN, Pt–D@CN, and Pt–P@CN are formed with g‐C3N4. Among these assemblies, the Pt(II) acetylide‐based composite materials Pt–D@CN and Pt–P@CN with bulk heterojunction morphologies and extremely low Pt weight ratios of 0.19% and 0.24%, respectively, exhibit the fastest charge transfer and best light‐harvesting efficiencies. Among the tested assemblies, 10 mg Pt–P@CN without any Pt metal additives exhibits a significantly improved photocatalytic H2 generation rate of 1.38 µmol h−1 under simulated sunlight irradiation (AM1.5G, filter), which is sixfold higher than that of the pristine g‐C3N4.