Tandem Catalysis of CuNi Bimetallic MOFs Boosting Nitrate Reduction for Ammonia Production

doi:10.15541/jim20250321

Abstract

Abstract:

Electrocatalytic nitrate reduction reaction (NO₃RR), as a green technology for producing ammonia and purifying wastewater, faces challenges in terms of nitrite intermediate accumulation and competitive hydrogen evolution reactions. Tandem catalytic strategy (NO₃^-→NO₂^-→NH₃) is expected to significantly improve the rate and selectivity of ammonia production. Therefore, designing and constructing dual active sites with different catalytic properties contributes to improving reaction activity. Herein, a CuNi bimetallic metal organic framework (MOF) tandem catalytic system using well-defined MOFs as templates was constructed through simple hydrothermal synthesis. The research results indicated that Cu active sites could efficiently catalyze the reduction of NO₃^- to NO₂^-, while Ni sites exhibited excellent active hydrogen species ^*H supply capacity and NO₂^- conversion efficiency, forming an efficient tandem catalytic mechanism with Cu sites, and achieving a Faraday efficiency of up to 90.1% for ammonia synthesis and an ammonia yield of 28.8 mg·h^-1·mg_cat^-1. In addition, the bimetallic MOFs catalyst showed excellent cycling stability without any degradation in ammonia synthesis after multiple cycling tests. This work provides new insights for the design and optimization of high-performance tandem catalysts.

Key words: ammonia production, nitrate reduction reaction, bimetallic, metal organic framework, tandem catalysis

CLC Number:

O646

WANG Meng, CAO Leilei, GOU Wangyan, CHENG Yayi, ZHAN Qi, YUAN Menglei. Tandem Catalysis of CuNi Bimetallic MOFs Boosting Nitrate Reduction for Ammonia Production[J]. Journal of Inorganic Materials, 2026, 41(5): 628-636.

Figures/Tables 17

Fig. 1 SEM images of the prepared catalysts (a) Ni-BDP; (b) CuNi-BDP; (c) Cu2Ni-BDP

Fig. 2 (a) TEM image and (b) elemental mappings of CuNi-BDP

Fig. 3 XRD patterns of the prepared catalysts

Fig. 4 XPS spectra of the prepared catalysts (a, b) Total surveys of (a) Ni-BDP and (b) CuNi-BDP; (c, d) High resolution XPS spectra of (c) Ni2p and (d) Cu2p for Ni-BDP and CuNi-BDP

Fig. 5 FT-IR spectra of the prepared catalysts

Fig. 6 Electrocatalytic activity for NO3RR (a) LSV curves of Ni-BDP, CuNi-BDP and Cu2Ni-BDP in 1 mol/L KOH+0.1 mol/L KNO3; (b) NH3 yield rates and (c) FE at various potential for Ni-BDP, CuNi-BDP and Cu2Ni-BDP; (d) Double-layer capacitance and (e) Nyquist plots of Ni-BDP, CuNi-BDP and Cu2Ni-BDP; (f) Cycling tests of CuNi-BDP at -0.5 V (vs. RHE). Colorful figures are available on website

Fig. 7 (a) Yield rates and (b) FE of NO2- byproduct for CuNi-BDP

Fig. 8 Schematic diagram of reaction mechanism

Fig. S1 (a) LSV curves in different electrolytes and (b) chronoamperometric (CA) curves at various potential of Ni-BDP

Fig. S2 (a) LSV curves in different electrolytes and (b) CA curves at various potential of CuNi-BDP

Fig. S3 (a) LSV curves in different electrolytes and (b) CA curves at various potential of Cu2Ni-BDP

Fig. S4 (a) UV-Vis spectra of NH3 with different concentrations and (b) corresponding calibration curve

Fig. S5 (a) UV-Vis spectra of NO2- with different concentrations and (b) corresponding calibration curve

Fig. S6 CV curves at different scan rates for catalysts (a) Ni-BDP; (b) CuNi-BDP; (c) Cu2Ni-BDP

Fig. S7 (a) SEM image, (b) XRD pattern and (c, d) XPS spectra of CuNi-BDP after NO3RR cycle test

Table S1 ICP-MS data of CuNi-BDP and Cu2Ni-BDP

Catalyst	Element	Metal content/% (in mass)	Ni/Cu atomic ratio
CuNi-BDP	Ni	15.66	8.56
CuNi-BDP	Cu	1.98	8.56
Cu₂Ni-BDP	Ni	13.45	3.99
Cu₂Ni-BDP	Cu	3.65	3.99

Table S2 Comparison of NO3RR performance for different bimetallic catalysts

Catalyst	NO₃^- concentration	NH₃ FE	NH₃ yield rate	Ref.
CuNi-BDP	0.1 mol/L	90.1% (-0.5 V)	28.8 mg·h^-1·mg_cat^-1 (-0.7 V)	This work
Fe/Cu-HNG	0.1 mol/L	92.5% (−0.3 V)	18.4 mg·h^-1·mg_cat^-1(-0.5 V)	[S1]
Cu₇Ni₃/OMC	500 mg/L	78.9% (−0.4 V)	0.237 mg·h^-1·mg_cat^-1(-0.8 V)	[S2]
Co_3-_xNi_xO₄	0.1 mol/L	94.9% (-1.0 V)	20 mg·h^-1·cm^-2(-1.0 V)	[S3]
Fe-V₂O₅	0.1 mol/L	97.1% (-0.7 V)	12.5 mg·h^-1·cm^-2(-0.7 V)	[S4]
Fe₃O₄@TiO₂/TP	0.1 mol/L	88.4% (-0.7 V)	12.4 mg·h^-1·cm^-2(-1.1 V)	[S5]
Ru₁Cu₁₀/rGO	100 mg/L	98% (-0.05 V)	6.46 mg·h^-1·cm^-2(-0.6 V)	[S6]
Cu₄₉Fe₁	200 mg/L	94.5% (-0.74 V)	3.91 mg·h^-1·cm^-2(-0.74 V)	[S7]
Au/Cu SAAs	100 mg/L	98.3% (-0.8 V)	3.28 mg·h^-1·cm^-2(-0.8 V)	[S8]
Ru/WO₃₋_x	0.1 mol/L	95.1% (0 V)	12.38 mg·h^-1·cm^-2(-0.6 V)	[S9]
Ni₃Co₆S₈	50 mg/L	85.3% (-0.4 V)	2.338 mg·h^-1·cm^-2 (-0.4 V)	[S10]
Pt-Fe₃O₄	0.1 mol/L	80.7% (-0.8 V)	5.42 mg·h^-1·mg^-1 (-0.8 V)	[S11]
Cu₃P-Ni₂P/CP	200 mg/L	95.25% (-0.6 V)	3.21 mg·h^-1·cm^-2(-0.6 V)	[S12]
Cu-Co₃O₄	5 mmol/L	93.77% (-1.0 V)	3.23 mg·h^-1·cm^-2(-1.0 V)	[S13]
Cu_xCo_yO-NC	0.1 mol/L	97.9% (-0.79 V)	7.65 mg·h^-1·cm^-2(-0.79 V)	[S14]
Pd-CoO_x	0.1 mol/L	98.7% (-0.4 V)	30.3 mg·h^-1·cm^-2(-0.4 V)	[S15]

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