优化结晶度的CrS/CoS_(2)少层异质结非晶/晶态界面耦合增强水裂解和甲醇辅助节能制氢

Amorphous-Crystalline Interfaces Coupling of CrS/CoS_(2)Few-Layer Heterojunction with Optimized Crystallinity Boosted for Water-Splitting and Methanol-Assisted Energy-Saving Hydrogen Production

由于电催化剂中的非晶区和结晶区具有不同的物理化学性质,因此非晶化/结晶化工程成为提高电解水催化动力学的重要策略。然而,在微观环境中有效地调控催化剂的结晶度仍然是一个严峻的挑战。本文介绍了一种可调节结晶度的新型CrS/CoS_(2)异质结构,该异质结对氢气析出反应(HER)和氧气析出反应(OER)都具有高效的催化活性。Cr―S―Co键的重新分配引起的d带中心移动有助于调节中间体H^(*)和OOH^(*)在催化剂表面的吸附能力,从而优化HER和OER的决速步骤。在最佳条件下,非晶态CrS和高度结晶的CoS_(2)异质结(A-CrS/HC-CoS_(2))在HER和OER均表现出优异的催化活性,分别为90.6 mV(10 mA∙cm^(-2),HER)和370.5 mV(50 mA∙cm^(-2),OER)。非晶/高晶结构有利于A-CrS/HC-CoS_(2)在水电解过程中的结构和成分演变,因此具有出色的稳定性。作为甲醇辅助节能制氢装置中的双功能催化剂,A-CrS/HC-CoS_(2)仅需1.51 V的低槽电压即可达到10 mA∙cm^(-2)的电流密度,证明其是理想的金属基催化剂的候选材料。本研究为双功能过渡金属化合物电催化剂在非晶态/晶态异质结构中通过结晶度调控来提高催化活性和稳定性提供了重要启示。

Large-scale hydrogen production through the electrochemical water splitting technique is an important way for addressing the impending energy and environmental crisis.This approach requires highly efficient and robust bifunctional cost-effective electrocatalysts.Engineering amorphous and crystalline phases within electrocatalysts is a key method for enhancing the catalytic kinetics of water electrolysis,due to their unique physicochemical properties.The interface and amorphous regions constructed within heterostructures serve as highly active sites that play a crucial role in electrochemical reactions.On the other hand,highly crystalline regions within the heterostructure demonstrated high tolerance in harsh environments,which helps to improve the stability of the overall catalyst.However,effectively tailoring the crystalline state of catalysts within a microenvironment presents a significant challenge.Herein,construction of a novel CrS/CoS_(2)heterojunction with precise control over crystallinity were presented.The optimized amorphous CrS/highly crystalline CoS_(2)heterojunction(A-CrS/HC-CoS_(2))exhibits a low overpotential of 90.6 mV(at 10 mA∙cm^(-2))and 370.5 mV(at 50 mA∙cm^(-2))for hydrogen evolution reaction(HER)and oxygen evolution reaction(OER),respectively.X-ray photoelectron spectroscopy(XPS)and density functional theory(DFT)calculations reveal that charge redistribution induces variations in the d-band center value at the A-CrS/HC-CoS_(2)heterostructure interface,enhancing the catalytic activity for both HER and OER.The displacement of the d-band due to charge redistribution in the Cr―S―Co bond within A-CrS/HC-CoS_(2)contributes to the modulation of the adsorption capacity of H^(*)and OOH^(*)intermediates on the catalyst surface,thereby optimizing the rate-determining step for HER and OER.The amorphous/highly crystalline structure also facilitates the structural and compositional evolution of A-CrS/HC-CoS_(2)during water electrolysis,ensuring excellent stability.As a bifunctional catalyst in a methanol-assisted energy-saving hydrogen production device,A-CrS/HC-CoS_(2)operates at a low cell voltage of 1.51 V to deliver a current density of 10 mA∙cm^(-2),making it a promising candidate among metal-based catalysts.The well-preserved amorphous/crystalline heterointerfaces in A-CrS/HC-CoS_(2),along with favorable changes in surface composition,contribute to robust HER and OER stability.This work provides valuable insights into the manipulation of catalytic activity through crystalline control within amorphous/crystalline heterojunctions for bifunctional transition metal compound electrocatalysts.