Preparation method and application of heterogeneous heterogeneous interface biomass carbon supported catalyst

Abstract

The application discloses a preparation method of a heterogeneous multi-phase interface biomass carbon supported catalyst, and specifically comprises the following steps: soaking an endogenous chromium coordination collagen fiber precursor in an ethanol / water mixed solution, washing and drying to obtain pretreated powder; pre-carbonizing the pretreated powder in an inert atmosphere to obtain a stable carbon precursor; performing acid activation treatment on the stable carbon precursor, washing and drying to obtain a chromium-containing nitrogen-oxygen-carbon skeleton; mixing the chromium-containing nitrogen-oxygen-carbon skeleton with a nickel salt precursor, impregnating and loading, drying, and then performing carbonization in an inert atmosphere. Through a step-by-step process route of pretreatment-pre-pyrolysis-acid activation-Ni post introduction-high temperature carbonization, the application constructs a heterogeneous multi-phase interface catalytic material containing a continuous biomass carbon skeleton, a Cr-based phase and a Ni species. The Cr / N doped carbon skeleton can induce selective deposition of Ni, inhibit high-temperature sintering, form small-size and high-dispersion particles, so that more active sites, higher interface utilization and more stable metal particles are obtained.

Description

Technical Field

[0001] This invention belongs to the field of catalytic material preparation technology, specifically relating to the preparation method of heterogeneous multiphase interface biomass carbon-supported catalysts, and also to the application of heterogeneous multiphase interface biomass carbon-supported catalysts. Background Technology

[0002] Alkaline water electrolysis for hydrogen production is an important green hydrogen production route. However, the reaction kinetics of the water molecule dissociation step involved in the hydrogen evolution reaction under alkaline conditions are relatively slow, thus placing high demands on the activity and stability of the catalyst. Among existing highly active hydrogen evolution catalysts, noble metal materials, while possessing excellent performance, are costly and have limited reserves, hindering large-scale application. In contrast, non-noble metal catalysts offer advantages such as lower cost and wider availability, making them more suitable for practical applications.

[0003] Among non-precious metal electrocatalytic materials, carbon-supported metal composites have attracted widespread attention due to their combination of good conductivity, rich structural tunability, and designable surface chemical characteristics. Biomass-derived carbon materials are generally widely available and inexpensive, and often retain natural porous structures and surface functional groups, making them suitable as catalyst supports. Chromium-containing waste leather is a special type of biomass raw material that combines the characteristics of a natural collagen fiber framework and native metal elements. On the one hand, its inherent collagen fiber network can be transformed into a continuous fibrous or porous carbon framework after appropriate heat treatment; on the other hand, the chromium element retained therein can evolve into a Cr-based active phase during subsequent heat treatment, thus providing a natural basis for constructing metal / support heterogeneous interfaces. Therefore, chromium-containing waste leather can not only be used as a general carbon source, but also provide both framework inheritance and in-situ Cr phase source, which provides conditions for developing structurally integrated and interface-tunable electrocatalytic materials.

[0004] However, most existing technologies employ direct mixing of metal precursors and biomass feedstock followed by high-temperature carbonization, or simultaneous carbonization, phase formation, and metal loading before the support has stabilized. While these methods are relatively simple, they typically suffer from the following drawbacks: First, the support framework formation and metal species nucleation and growth occur simultaneously, with variables coupled, making it difficult to distinguish the true contribution of structural evolution and metal size effects. Second, direct high-temperature treatment easily leads to the collapse of the original fiber framework and damage to the pore structure, hindering the formation of a stable and continuous support. Third, subsequently introduced metal components such as Ni are prone to migration, sintering, and agglomeration during simultaneous heat treatment; furthermore, the metal grain size, microstructure, and metal-support interface contact state of the resulting material change synchronously with differences in support structure, resulting in a lack of a unified comparative benchmark for different samples and making it difficult to accurately determine intrinsic performance differences. Fourth, with simultaneous changes in support composition and interface configuration, differences in hydrogen evolution performance are difficult to attribute clearly, hindering the establishment of a clear and reliable structure-performance relationship.

[0005] Therefore, there is an urgent need to develop a novel preparation strategy that first achieves stable preservation of the support framework structure and multi-element chemical environment, and then directionally introduces Ni active components on a unified support platform and precisely controls their microstructure. This strategy can minimize the interference caused by intrinsic differences in the support, clearly identify the influence of Ni grain size, dispersion, and interface structure on catalytic hydrogen evolution performance, and thus improve the controllability of catalytic material structure design and the reliability of structure-activity attribution. Summary of the Invention

[0006] The primary objective of this invention is to provide a method for preparing a heterogeneous multiphase interface biomass carbon-supported catalyst, which enables tunable loading of Ni species configuration and size on an inherited support.

[0007] A second objective of this invention is to provide a heterogeneous multiphase interface biomass carbon-supported catalyst.

[0008] A third objective of this invention is to provide the application of heterogeneous multiphase interface biomass carbon-supported catalysts in the hydrogen evolution reaction of alkaline electrolytes.

[0009] The technical solution adopted in this invention is a method for preparing a heterogeneous multiphase interface biomass carbon-supported catalyst, which is implemented according to the following steps: Step 1: Soak, wash, dry and pulverize the endogenous chromium-coordinated collagen fiber precursor in an ethanol / water mixed solution to obtain a pretreated powder; Step 2: Pre-carbonize the pretreated powder under an inert atmosphere to obtain a stable carbon precursor; Step 3: The stable carbon precursor is acid activated, washed until neutral and dried to obtain a chromium-containing nitrogen-oxygen carbon framework. Step 4: The chromium-containing nitrogen-oxygen carbon framework is mixed with the nickel salt precursor and impregnated and supported. After drying, it is carbonized under an inert atmosphere to obtain a heterogeneous multiphase interface biomass carbon-supported catalyst.

[0010] The invention is further characterized in that, In step 1, the immersion time of the collagen fiber precursor containing endogenous chromium in the ethanol / water mixed solution is 24-48 h; the drying temperature is 40-80℃ and the drying time is 2-8 h.

[0011] In step 2, the pre-carbonization conditions are as follows: under an inert atmosphere, the temperature is increased to 250-400℃ at a heating rate of 3-10℃ / min, and held at that temperature for 0.5-3h.

[0012] In step 3, acid activation is achieved by soaking in hydrochloric acid aqueous solution with a concentration of 0.5~2 mol / L for 1~4 h; drying temperature is 40~80℃ and drying time is 8~16 h.

[0013] In step 4, the impregnation time is 0.5-3 hours; the mass ratio of the chromium-containing nitrogen-oxygen-carbon skeleton to the nickel salt precursor is 1:0.1~1.

[0014] The carbonization conditions are as follows: under an inert atmosphere, the temperature is increased to 700-900℃ at a heating rate of 3-10℃ / min, and held for 1-5 hours.

[0015] Another technical solution adopted in this invention is a method for preparing heterogeneous multiphase interface biomass carbon-supported catalysts. The heterogeneous multiphase interface biomass carbon-supported catalysts include a continuous carbon skeleton, a Cr-based phase evolved from primary chromium species in an endogenous chromium-coordinated collagen fiber precursor, and Ni species supported on the surface and pores of the carbon skeleton. The Ni species and the Cr-based phase form a heterogeneous multiphase interface. The Cr-based phase includes one or more of Cr2O3, CrN, or their composite phases, and the Ni species includes one or more of Ni, NiO, or Ni / NiO composites.

[0016] The beneficial effects of this invention are as follows: using chrome-tanned wet blue leather as a precursor, a morphology-inherited Cr / N-doped carbon framework is constructed through two-step pyrolysis, and Ni species are deposited in a confined manner and their size controlled on its surface. The wet blue leather retains its fibrous structure after pre-pyrolysis, avoiding collapse and disordered agglomeration caused by direct high-temperature pyrolysis. Furthermore, the Cr in the wet blue leather is not an impurity; the inherent Cr component can be transformed into a CrN-based crystalline phase structure, accompanied by the formation of Cr-N. X and a small amount of CrO X Isostatic coordination / defect sites; Cr / N doped carbon framework can induce selective Ni deposition, suppress high-temperature sintering, and form a matrix dominated by metallic Ni with a small amount of NiO on the surface. X / Ni δ+ The high-dispersion Ni-based nanoparticles have performance advantages mainly in terms of more active sites, higher interface utilization, and more stable metal particles. Therefore, their catalytic activity and stability are superior to materials prepared by one-pot method or gelatin-assisted route. Attached Figure Description

[0017] Figure 1 This is a SEM image of WL wet blue leather raw material; Figure 2 This is a SEM image of a WLC-300℃ pre-carbonized sample; Figure 3 This is a SEM image of the Cr / WLC sample; Figure 4 This is a low-magnification SEM image of the Ni-Cr / WLC-0.5 sample; Figure 5 This is a SEM image of the Ni-Cr / WLC-0.5 sample; Figure 6This is a high-magnification SEM image of the Ni-Cr / WLC-0.5 sample; Figure 7 This is the elemental mapping diagram of the Ni-Cr / WLC-0.5 sample; Figure 8 This is a TEM image of the Ni-Cr / WLC-0.5 sample; Figure 9 This is an HRTEM image of the Ni-Cr / WLC-0.5 sample; Figure 10 This is a magnified view of the lattice fringes of the Ni-Cr / WLC-0.5 sample; Figure 11 This is the HAADF-STEM and Cr / Ni elemental distribution map of the Ni-Cr / WLC-0.5 sample; Figure 12 These are the XRD patterns of different samples; Figure 13 This is the N2 adsorption-desorption isotherm diagram of the Ni-Cr / WLC-0.5 sample; Figure 14 This is the XPS full spectrum of the Ni-Cr / WLC-0.5 sample; Figure 15 This is the N 1s high-resolution XPS image of the Ni-Cr / WLC-0.5 sample; Figure 16 This is a high-resolution XPS image of Cr 2p in the Ni-Cr / WLC-0.5 sample; Figure 17 This is a high-resolution XPS image of Ni 2p in the Ni-Cr / WLC-0.5 sample; Figure 18 These are the HER polarization curves and LSV plots for different samples; Figure 19 These are Tafel slope plots for different samples; Figure 20 These are EIS electrochemical impedance spectroscopy (EIS) plots of different samples; Figure 21 This is a comparison of Cdl values ​​for different samples; Figure 22 This is a comparison of LSV before and after the cyclic stability test of the Ni-Cr / WLC-0.5 sample; Figure 23 This is a graph showing the long-term stability test results of the Ni-Cr / WLC-0.5 sample. Detailed Implementation

[0018] The present invention will now be described in detail with reference to specific embodiments and accompanying drawings.

[0019] The preparation method of the heterogeneous multiphase interface biomass carbon-supported catalyst of the present invention is specifically implemented according to the following steps: Step 1: The endogenous chromium-coordinated collagen fiber precursor is immersed in an ethanol / water mixed solution, followed by washing, drying and pulverizing to obtain a pretreated powder; The immersion time of the endogenous chromium-coordinated collagen fiber precursor in the ethanol / water mixed solution is 24~48h, preferably 36h; The drying temperature is 40-80℃, and the drying time is 2-8 hours. Step 2: Pre-carbonize the pretreated powder under an inert atmosphere to obtain a stable carbon precursor; The pre-carbonization conditions are as follows: under an inert atmosphere, the temperature is increased to 250-400℃ at a heating rate of 3-10℃ / min and held for 0.5-3h; preferably, the temperature is increased to 300℃ at a heating rate of 5℃ / min and held for 1h. By preheating and decomposing to stabilize the biomass skeleton, the fibrous structure and multi-element environment of the leather-derived carbon skeleton can be better preserved in subsequent high-temperature treatment. Step 3: The stable carbon precursor is acid activated, then washed until neutral and dried to obtain WLC containing chromium nitrogen oxygen carbon framework. Acid activation is achieved by soaking in hydrochloric acid aqueous solution with a concentration of 0.5~2 mol / L, preferably 1 mol / L, for a treatment time of 1~4 h, preferably 2 h. The acid-activated sample is washed until neutral and then vacuum dried at 40-80°C for 8-16 hours, preferably at 60°C for 12 hours. Acid activation helps remove impurities, unclog pores, and expose surface functional groups, thereby obtaining a support with a more defined surface chemical environment and more accessible loading sites.

[0020] Step 4: The chromium-containing nitrogen-oxygen carbon skeleton is contacted, mixed with the nickel salt precursor, and impregnated for 0.5-3 hours. After drying, it is subjected to high-temperature carbonization in an inert atmosphere, so that the Cr matrix phase and Ni species evolved from the primary chromium species in the chromium-containing waste leather are loaded on the continuous carbon skeleton and form a heterogeneous multiphase interface, thereby obtaining a heterogeneous multiphase interface biomass carbon-supported catalyst.

[0021] The mass ratio of the chromium-containing nitrogen-oxygen-carbon framework to the nickel salt precursor is 1:0.1~1, preferably 1:0.5; The high-temperature carbonization conditions are as follows: under an inert atmosphere, the temperature is increased to 700-900℃ at a heating rate of 3-10℃ / min and held for 1-5 hours; preferably, the temperature is increased to 800℃ at a heating rate of 5℃ / min and held for 3 hours.

[0022] The heterogeneous multiphase interface biomass carbon-supported catalyst comprises a continuous carbon skeleton, a Cr-based phase evolved from primary chromium species in chromium-containing waste leather, and Ni species supported on the surface and in the pores of the carbon skeleton. The Ni species and the Cr-based phase form a heterogeneous multiphase interface.

[0023] The Cr-based phase includes one or more of Cr2O3, CrN, or their composite phases, and the Ni species includes one or more of Ni, NiO, or Ni / NiO composite species.

[0024] The method for preparing the heterogeneous multiphase interface biomass carbon-supported catalyst of the present invention firstly involves soaking an endogenous chromium-coordinated collagen fiber precursor in an ethanol / water mixture, washing it with deionized water, drying it, and pulverizing it to obtain a pretreated powder. Subsequently, the pretreated powder is pre-pyrolyzed under an inert atmosphere to preferentially complete the initial solidification of the framework at a lower temperature, resulting in a stabilized carbon precursor that retains the rudimentary fiber framework and the original multi-element environment. The stabilized carbon precursor is then acid-activated to remove impurities, clear pores, and expose surface functional groups, obtaining a chromium-nitrogen-oxygen carbon framework support. Finally, a nickel salt precursor is introduced onto this pre-formed support, followed by impregnation, evaporation, and high-temperature carbonization, allowing Ni species to be selectively loaded onto the surface and pores of the continuous carbon framework, and to construct a heterogeneous multiphase interface with the Cr-based phase evolved from the primary chromium species, thereby obtaining the target catalyst.

[0025] The core of this invention lies not in simply introducing Ni or Cr matrix phases, but in establishing a stepwise, comparable interface construction method. Specifically, the initial fibrous prototype of the carbon skeleton derived from chromium-containing waste leather is first preserved through pre-pyrolysis at approximately 300°C, while maintaining the original multi-element environment as much as possible. Then, acid activation is used to obtain a unified support with a relatively stable skeleton structure and surface sites. Based on this, Ni species are introduced and controlled during subsequent heat treatment at approximately 800°C, allowing different samples to share the same source, similar composition, and similar inherited skeleton, with major differences only in the size, dispersion state, and interfacial contact mode of the Ni species. Because the differences in the support are effectively compressed, the differences in hydrogen evolution performance of different samples can more directly reflect the role of Ni configuration and Ni / CrN matrix interface, making interface comparison clearer and performance attribution more reliable.

[0026] Example 1: Preparation of WLC with a chromium-containing nitrogen-oxygen-carbon framework The endogenous chromium-coordinated collagen fiber precursor was immersed in a mixed solution of ethanol and water for 36 h, followed by repeated washing with deionized water. The washed sample was dried at 80 °C for 6 h and ground into a fine powder. The obtained powder was placed under an argon atmosphere and heated to 300 °C at a heating rate of 5 °C / min and held at that temperature for 1 h to obtain a pre-carbonized product. The pre-carbonized product was ground and treated with 1 mol / L hydrochloric acid for 2 h to remove tar and ash and expose surface functional groups. It was then washed with deionized water until neutral and vacuum dried at 60 °C for 12 h to obtain a chromium-containing nitrogen-oxygen-carbon framework WLC.

[0027] Example 2: Preparation of Ni-Cr / WLC-0.1 Weigh the WLC obtained in Example 1 and mix it with Ni(NO3)2·6H2O in 20 mL of deionized water at a WLC:nickel salt mass ratio of 2:1, wherein the nickel metal mass in the nickel precursor is 0.1 g. Heat to 90 °C under stirring and evaporate to dryness. Then, under an argon atmosphere, heat to 800 °C at 5 °C / min and hold for 3 h to obtain the sample Ni-Cr / WLC-0.1.

[0028] Example 3: Preparation of Ni-Cr / WLC-0.5 Weigh the WLC obtained in Example 1 and mix it with Ni(NO3)2·6H2O in 20 mL of deionized water at a WLC:nickel salt mass ratio of 2:1, wherein the nickel metal mass in the nickel precursor is 0.5 g. Heat to 90 °C under stirring and evaporate to dryness. Then, under an argon atmosphere, heat to 800 °C at 5 °C / min and hold for 3 h to obtain the sample Ni-Cr / WLC-0.5.

[0029] Example 4: Preparation of Ni-Cr / WLC-1 Weigh the WLC obtained in Example 1 and mix it with Ni(NO3)2·6H2O in 20 mL of deionized water at a WLC:nickel salt mass ratio of 2:1, wherein the nickel metal mass in the nickel precursor is 1.0 g. Heat to 90 °C under stirring and evaporate to dryness. Then, under an argon atmosphere, heat to 800 °C at 5 °C / min and hold for 3 h to obtain sample Ni-Cr / WLC-1.

[0030] Examples 2-4 are a set of comparable samples constructed by adjusting the amount of nickel precursor added, based on the same preparation source, prepyrolysis, and acid-activated support. The design focus of this set of samples was not on changing the support itself, but rather on maintaining consistency in the source, framework, and elemental environment of the inherited support, only adjusting the loading, size, and interfacial contact state of Ni species. This design allows for a clearer examination of the effects of Ni configuration changes on particle dispersion, interface formation, and hydrogen evolution performance, thereby reducing comparison bias caused by differences in the support and improving the reliability of interfacial effect analysis.

[0031] Comparative Example 1: Preparation of Unactivated Samples The endogenous chromium-coordinated collagen fiber precursor was treated according to the pretreatment and precarbonization steps in Example 1, but the precarbonization product was not activated by hydrochloric acid. It was directly mixed with 0.5 g of nickel nitrate hexahydrate and then subjected to subsequent evaporation and high-temperature carbonization. The other conditions were the same as in Example 3, and an un-acid-activated control sample was obtained. The purpose of setting up this comparative example is to illustrate the effect of the acid activation step on the exposure of material surface sites and the loading behavior of Ni species.

[0032] Comparative Example 2: Preparation of one-step direct carbonization samples Pretreated endogenous chromium-coordinated collagen fiber precursor powder was mixed with 0.5 g of nickel nitrate hexahydrate in 20 mL of deionized water. After stirring and evaporating to dryness, without pre-carbonization and acid activation, the mixture was directly heated to 800 °C at a heating rate of 5 °C / min and held for 3 h under an argon atmosphere to obtain a one-step direct carbonization control sample. The purpose of setting up this comparative example is to compare it with the stepwise route of prepyrolysis-acid activation-Ni introduction-high temperature carbonization of the present invention, to show that the support formation and Ni growth occur simultaneously under the one-step direct carbonization condition, which easily leads to insufficient scaffold inheritance, limited Ni dispersion, and unclear interface configuration; at the same time, it proves that the strategy of first shaping the support and then controlling Ni in the present invention is more conducive to obtaining a unified comparison platform and clearer interface differences.

[0033] η of Ni-Cr / WLC-0.5 10 The lowest value was 198 mV, and the Tafel slope was the lowest at 113 mV dec. -1 ECSA was the highest at 96.3 cm. 2This indicates that the sample exhibits the highest activity, the fastest reaction kinetics, and the most exposed active sites. This is mainly attributed to the fact that the Cr / N / O functionalized carbon framework formed during the pyrolysis of chrome-tanned wet blue leather effectively anchors Ni species and promotes the formation of a tightly connected composite active interface between Ni and chromium-based species such as CrN and Cr2O3. In contrast, the comparative samples, due to the lack of a reasonable Ni-Cr synergistic effect, poor metal particle dispersion, or insufficient number of active sites, exhibit relatively low catalytic activity and stability. In particular, in the example sample with an appropriate amount of Ni loading, the Ni nanoparticles are uniformly dispersed and have a moderate particle size, ensuring a large number of exposed active sites while avoiding particle agglomeration caused by excessive metal, thus showing superior reaction performance compared to the comparative samples. This demonstrates that the present invention achieves a balance between the resource utilization of waste leather and the improvement of high-efficiency catalytic performance through the synergistic construction of wet blue leather-derived carbon support and Ni-Cr active components.

[0034] Morphological characterization description The catalyst prepared by the method of this invention can better retain the continuous fibrous or porous structure of the carbon skeleton derived from waste leather, indicating that the original biomass skeleton has achieved preliminary stability after pre-pyrolysis at 300℃ and can still maintain certain inherited morphological characteristics in subsequent high-temperature treatment. Based on this unified support platform, Ni species can be further loaded onto the surface and pores of the carbon skeleton; under moderate Ni loading conditions, Ni species exist in a more dispersed nanoscale form and form more sufficient interfacial contact with the Cr-based phase; when the amount of Ni precursor added continues to increase, the Ni particle size increases, the aggregation tendency is enhanced, and the interfacial distribution tends to be non-uniform. The above results show that the main morphological differences between the samples of this invention are mainly reflected in the configuration and size changes of Ni species, while the overall support skeleton remains comparable, providing a more unified basis for subsequent comparison of interfacial interactions and electrocatalytic performance.

[0035] Phase and surface chemistry description The catalyst obtained by this invention contains a Cr-based phase evolved from primary chromium species in chromium-containing waste leather. Simultaneously, Ni species and their associated oxidation state signals can be detected, indicating the formation of a composite structure where the Cr-based phase, Ni species, and a continuous carbon framework coexist after high-temperature treatment. Since Ni is further introduced and regulated on a pre-formed support, different samples maintain a high degree of consistency in the overall framework origin and elemental environment. The main differences lie in the dispersion degree, size characteristics, and interfacial contact mode between Ni species and the Cr-based phase. Compared to the complex coupling caused by the simultaneous evolution of the support and metal in a one-step method, this invention is more advantageous for identifying the influence of Ni configuration changes on the interfacial structure at the phase and surface chemistry levels.

[0036] Pore ​​structure and surface properties description Acid activation treatment not only helps remove impurities clogging the pores but also increases the exposure of surface functional groups and accessible loading sites, making the resulting support more suitable as a subsequent Ni loading platform in terms of framework structure and surface chemical environment. Since this platform forms before Ni introduction, the Ni precursor can be wetted, adsorbed, and transformed in a more uniform pore and surface environment, thereby enhancing the comparability between different samples and improving the feasibility of independent analysis of Ni size and interface effects.

[0037] Electrocatalytic application results description When the catalysts obtained in the above examples were used for the hydrogen evolution reaction (HER) in alkaline electrolytes, the prepared catalysts exhibited good HER activity and stability. It is worth noting that the different samples in this invention were not based on completely different supports, but rather on inherited support platforms formed by the same pre-pyrolysis and acid activation. The configuration, size, and interfacial contact state of Ni species were changed by adjusting the amount of Ni precursor added. Therefore, when different samples exhibit significant HER differences, these differences can be attributed more to Ni-related interfacial factors than to drastic changes in support source, framework morphology, or overall composition. The results show that under appropriate Ni loading conditions, Ni species can be anchored in a more dispersed state on the surface of the waste leather carbon framework and form a more effective heterogeneous multiphase interface with the Cr-based phase, thus better facilitating interfacial synergy. However, when the Ni loading is too high, the Ni particle size increases, aggregation intensifies, and interfacial effectiveness decreases, which is detrimental to further improving HER performance. This demonstrates that controlling the Ni configuration on a unified support is an effective way to establish clear interfacial comparisons and optimize catalytic performance.

[0038] Example 5 Figure 1 The presence of distinct fiber bundle structure in wet blue leather (WL) indicates that it can serve as a carbon, nitrogen, and chromium source. Figure 2 It can be seen that after pre-carbonization at 300℃, wet blue leather can still maintain its original fiber skeleton, indicating that preheating plays a role in stabilizing the structure. Figure 3 This further illustrates that Cr in wet blue leather transforms and anchors to the carbon framework after pyrolysis, forming a Cr / WLC matrix. Therefore, it can be seen that wet blue leather is not only a carbon source, but also a precursor that simultaneously provides fiber templates, N doping sources, and intrinsic Cr sites.

[0039] Figures 4-7This study primarily describes the morphological changes and elemental composite structure after Ni introduction. The presence of numerous particles and a rough structure on the Ni-Cr / WLC-0.5 surface indicates the formation of abundant metal / metal compound particles after Ni loading. High-magnification SEM further reveals a denser particle distribution, indicating an increased number of active sites. Elemental mapping shows that Ni, Cr, and N coexist and are distributed on the carbon matrix, indicating that the material is a Ni-Cr-N / C composite system. A suitable amount of Ni can be successfully loaded onto the Cr / N functionalized carbon framework, forming a rich composite active structure.

[0040] Figures 8-11 Further TEM and high-resolution structural analysis confirmed the formation of the active interface. TEM showed that the nanoparticles were loaded onto the carbon matrix, indicating that the Ni-Cr species exhibited nanoscale dispersion characteristics. HRTEM and lattice fringe patterns showed that 0.239 nm corresponded to CrN(111) and 0.208 nm corresponded to Ni(111), indicating the simultaneous presence of CrN and metallic Ni in the sample. HAADF-STEM and Cr / Ni mapping further confirmed the contact and spatial correlation between Ni and Cr at the nanoscale. A composite nanoscale interface was formed between Ni, CrN / Cr species, and the carbon support, among which the Ni–CrN or Ni–Cr / NC interface was an important active structure for enhancing catalytic performance.

[0041] Figures 12-17 The main findings describe the crystal phase composition, pore structure, and surface electronic structure. XRD analysis confirms the presence of Ni, CrN, and Cr2O3 crystalline phases in the sample, indicating the formation of a distinct Ni-Cr composite phase after pyrolysis. N2 adsorption-desorption analysis shows that the Ni-Cr / WLC-0.5 sample has a superior pore structure and specific surface area compared to Cr / WLC, which facilitates the exposure of more active sites. XPS spectra confirm the presence of C, N, O, Cr, and Ni; N participates in metal coordination and electronic regulation of the carbon framework; Cr exists in Cr–N and Cr–O forms; and Ni exists in both metallic, surface-oxidized, and coordinated states. This demonstrates that the material exhibits a complex electronic structure in which Ni, Cr, N, O, and the carbon framework interact.

[0042] Example 6 Figures 18-23 This mainly illustrates the catalytic performance and stability of the samples. LSV plots show significant differences in HER activity among samples with different Ni loadings, with the Ni-Cr / WLC-0.5 sample exhibiting a higher current density at the same potential, indicating optimal activity. Tafel plots show that the Ni-Cr / WLC-0.5 sample has the lowest slope, approximately 113–115 mV dec. -1The high impedance indicates the fastest reaction kinetics. The EIS plot shows low impedance, indicating smoother charge transport. The Cdl plot shows that the Ni-Cr / WLC-0.5 sample has a larger electrochemical active area, representing more available active sites. Cyclic stability and long-term stability tests show that the sample exhibits minimal activity decay after repeated testing and continuous operation, demonstrating good structural stability and catalytic durability.

[0043] In summary, this invention constructs a heterogeneous multiphase interfacial catalytic material comprising a continuous biomass carbon framework, a Cr-based phase, and Ni species through a stepwise process route of pretreatment, prepyrolysis, acid activation, post-Ni introduction, and high-temperature carbonization. The key advantage lies in first preserving and stabilizing the skeletal structure and multi-elemental environment of the waste leather-derived support, and then selectively loading and configuring Ni species on a unified inherited support. This allows the main differences between different samples to focus on Ni size, dispersion state, and interfacial contact with the Cr-based phase. Compared to one-step or simultaneous phase formation methods, this invention is more conducive to obtaining comparable and attributable interfacial structures and provides a more reliable structural basis for differences in hydrogen evolution performance.

Claims

1. A method for preparing a heterogeneous multiphase interface biomass carbon-supported catalyst, characterized in that, The specific steps are as follows: Step 1: Soak the endogenous chromium-coordinated collagen fiber precursor in an ethanol / water mixed solution, wash, dry and pulverize to obtain a pretreated powder; Step 2: Pre-carbonize the pretreated powder under an inert atmosphere to obtain a stable carbon precursor; Step 3: The stable carbon precursor is acid activated, washed until neutral and dried to obtain a chromium-containing nitrogen-oxygen carbon framework. Step 4: The chromium-containing nitrogen-oxygen carbon framework is mixed with the nickel salt precursor and impregnated and supported. After drying, it is carbonized under an inert atmosphere to obtain a heterogeneous multiphase interface biomass carbon-supported catalyst.

2. The method for preparing the heterogeneous multiphase interface biomass carbon-supported catalyst as described in claim 1, characterized in that, In step 1, the immersion time of the endogenous chromium-coordinated collagen fiber precursor in the ethanol / water mixed solution is 24-48 h; the drying temperature is 40-80℃ and the drying time is 2-8 h.

3. The method for preparing the heterogeneous multiphase interface biomass carbon-supported catalyst as described in claim 1, characterized in that, In step 2, the pre-carbonization conditions are as follows: under an inert atmosphere, the temperature is increased to 250-400℃ at a heating rate of 3-10℃ / min, and held at that temperature for 0.5-3h.

4. The method for preparing the heterogeneous multiphase interface biomass carbon-supported catalyst as described in claim 1, characterized in that, In step 3, acid activation is performed by soaking in hydrochloric acid aqueous solution with a concentration of 0.5~2 mol / L for 1~4 h; drying temperature is 40~80℃ and drying time is 8~16 h.

5. The method for preparing the heterogeneous multiphase interface biomass carbon-supported catalyst as described in claim 1, characterized in that, In step 4, the impregnation time is 0.5-3 hours; the mass ratio of the chromium-containing nitrogen-oxygen-carbon skeleton to the nickel salt precursor is 1:0.1~1.

6. The method for preparing the heterogeneous multiphase interface biomass carbon-supported catalyst as described in claim 1, characterized in that, In step 4, the carbonization conditions are as follows: under an inert atmosphere, the temperature is increased to 700-900℃ at a heating rate of 3-10℃ / min, and held at that temperature for 1-5 hours.

7. The heterogeneous multiphase interfacial biomass carbon-supported catalyst prepared by the method according to any one of claims 1-6.

8. The heterogeneous multiphase interface biomass carbon-supported catalyst as described in claim 7, characterized in that, It comprises a continuous carbon skeleton, a Cr-based phase evolved from primary chromium species in chromium-containing waste leather, and Ni species loaded on the surface and pores of the carbon skeleton. The Ni species and the Cr-based phase form a heterogeneous multiphase interface. The Cr-based phase includes one or more of Cr2O3, CrN, or their composite phases, and the Ni species includes one or more of Ni, NiO, or Ni / NiO composite species.

9. The application of the heterogeneous multiphase interface biomass carbon supported catalyst as described in claim 8 in the hydrogen evolution reaction of alkaline electrolyte.

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