Hcp IrNi Electrocatalyst for Selective Nitrite Reduction
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing electrocatalysts for nitrite reduction to ammonia suffer from low activity, poor selectivity, and stability, with limited performance due to the challenges in synthesizing alloy nanomaterials with unconventional crystal phases and kinetic mismatches during the multistep reaction process.
Innovation Solution
The development of IrNi-based alloy nanostructures with an unconventional hexagonal close-packed phase, featuring a Ni-rich core and Ir-rich shell, synthesized via a one-pot solvothermal method, which enhances electron transfer and active hydrogen generation for efficient nitrite reduction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional fcc phase alloy nanomaterials are used, then the synthesis process is simpler, but the catalytic activity and selectivity for nitrite reduction are insufficient
Solution Approach 1:
The patent applies parameter changes by transitioning from conventional fcc phase to hcp phase crystal structure through controlled synthesis parameters (temperature, pressure, solvent composition). This phase transition enables superior catalytic activity for nitrite reduction while maintaining manageable synthesis complexity through systematic parameter optimization
Solution Approach 2:
The patent employs composite materials by creating IrNi alloy nanomaterials with specific hcp phase structure and core-shell configuration. The composite alloy structure combines Ir and Ni elements in a controlled arrangement that enhances catalytic performance for nitrite reduction to ammonia while managing synthesis complexity through defined compositional ratios
2Reliability
If alloy nanomaterials with unconventional crystal phases are synthesized, then catalytic performance improves, but the synthesis difficulty increases
Solution Approach 1:
The patent uses parameter changes by establishing specific synthesis conditions (temperature range, pressure, solvent type, precursor ratios) that favor hcp phase formation. These controlled parameter changes enable reliable production of stable catalytic materials while making the synthesis process reproducible and manageable
Solution Approach 2:
The patent applies preliminary action by pre-designing the synthesis pathway with predetermined steps for forming the hcp phase IrNi alloy. The synthesis protocol includes preliminary preparation of precursor solutions, controlled heating/pressurization sequences, and cooling procedures that ensure consistent formation of the desired crystal phase and core-shell structure
3Productivity
If monometallic nanomaterials are used, then the synthesis process is simpler, but the ability to adsorb and stabilize multiple intermediates is limited
Solution Approach 1:
The patent employs composite materials by creating IrNi alloy structure where Ir provides specific adsorption sites and Ni provides others, enabling simultaneous adsorption and stabilization of multiple intermediates in the nitrite reduction pathway. This composite approach increases reaction rate while managing complexity through defined compositional ratios
Solution Approach 2:
The patent applies local quality by creating core-shell structure where the interior (core) and exterior (shell) regions have different compositions and properties. The core region provides structural stability while the shell region provides catalytically active sites with optimized local composition for specific intermediate adsorption, enhancing overall reaction rate
4Productivity
If the electrocatalyst operates for extended periods, then productivity increases, but stability and durability decrease
Solution Approach 1:
The patent employs composite materials by creating IrNi alloy with hcp phase that maintains structural integrity during prolonged operation. The specific alloy composition and crystal phase provide resistance to degradation while maintaining high catalytic activity, enabling extended operation without significant loss of durability
Solution Approach 2:
The patent applies the inversion principle by designing the catalyst to resist degradation rather than accepting it. The hcp phase structure and core-shell configuration are specifically engineered to prevent common degradation pathways, allowing the catalyst to maintain both high productivity and durability over extended operation periods
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The IrNi-based nanostructures exhibit high Faradaic efficiency (up to 98.2%) and yield rate (34.6 mg h−1 mgcat−1) for ammonia synthesis, demonstrating superior catalytic durability and stability over 20 electrolysis cycles.
Implementation Method 1
electrocatalytic NO2− reduction reaction (NO2RR) enables the simultaneous removal of NO2− contaminant and production of valuable NH3
Implementation Method 2
it only requires a low energy input and avoids fossil fuel consumption and greenhouse gas emission
Implementation Method 3
synthesized via a one-pot solvothermal method
Data Source
AI summary
The present invention reports the general one-pot synthesis of IrNi-based nanostructures with unconventional hexagonal close-packed (hcp) phase. Notably, the as-synthesized hcp IrNi nanostructures demonstrate excellent catalytic performance towards electrochemical nitrite reduction for ammonia synthesis. Ex/in-situ characterizations and theoretical calculations reveal that the Ir—Ni interactions within hcp IrNi-based nanostructures improve electron transfer to benefit both nitrite activation and active hydrogen generation, leading to a stronger reaction trend of NO2RR by greatly reducing energy barriers of rate-determining step.