Nickel-molybdenum nitride nanoplate electrocatalysts for concurrent electrolytic hydrogen and formate productions

Abstract

Hydrogen production by electrocatalytic water splitting is an efficient and economical technology, however, is severely impeded by the kinetic-sluggish and low value-added anodic oxygen evolution reaction. Here we report the nickel-molybdenum-nitride nanoplates loaded on carbon fiber cloth (Ni-Mo-N/CFC), for the concurrent electrolytic productions of high-purity hydrogen at the cathode and value-added formate at the anode in low-cost alkaline glycerol solutions. Especially, when equipped with Ni-Mo-N/CFC at both anode and cathode, the established electrolyzer requires as low as 1.36 V of cell voltage to achieve 10 mA cm−2, which is 260 mV lower than that in alkaline aqueous solution. Moreover, high Faraday efficiencies of 99.7% for H2 evolution and 95.0% for formate production have been obtained. Based on the excellent electrochemical performances of Ni-Mo-N/CFC, electrolytic H2 and formate productions from the alkaline glycerol solutions are an energy-efficient and promising technology for the renewable and clean energy supply in the future.

Etching‐Doping Sedimentation Equilibrium Strategy: Accelerating Kinetics on Hollow Rh‐Doped CoFe‐Layered Double Hydroxides for Water Splitting

“…Tafel plots of the corresponding polarization curves are a feasible method to study the HER reaction pathway and kinetics of the electrocatalysts. [39,40] The smaller Tafel slope, the faster reaction rate. As shown in Figure 3b, the Tafel slope of Rh doped CoFe-ZLDH is as low as 42.8 mV decade −1 , which is much smaller than Rh-doped CoFe-LDH (63.6 mV decade −1 ), CoFe-ZLDH (100.1 mV decade −1 ), CoFe-LDH (84.9 mV decade −1 ), and NF (103.7 mV decade −1 ).…”

“…Considering these results, the reaction process driven by Rh doped CoFe-ZLDH follows the Volmer-Heyrovsky mechanism to achieve a rapidly increasing hydrogen evolution rate under the application of voltage. As shown in Figure 3c and Table S2 in the Supporting Information, Rh-doped CoFe-ZLDH outperforms many other previously reported state-of-art HER electrocatalysts, such as Rh 2 P, [41] L-Ag, [42] single atomic Co supported on phosphorized carbon nitride nanosheets (Co 1 /PCN), [43] NiMoO x -Ni(OH) 2 /NF, [44] interface catalyst consisting of atomic cobalt array covalently bound to distorted 1T MoS 2 nanosheets (SA Co-D 1T MoS 2 ), [45] Pt clusters in hollow mesoporous carbon spheres (Pt 5 /HMCS), [46] Ni-Fe nanoparticle (Ni-Fe NF), [39] oxygen vacancy enrich CoFe 2 O 4 (r-CFO), [47] CoFeP TAPs/Ni, [48] nickel-molybdenum-nitride nanoplates on carbon fiber cloth (Ni-Mo-N/CFC), [40] Ru SA -N-S-Ti 3 C 2 T x , [9] W-CoP NAs-CC, [49] MoP@NCHs-900, [50] Co 9 S 8 @C, [51] and Co 0.31 Mo 1.69 C/MXene/NC. [52] The cyclic voltammetry (CV) method was utilized to calculate the electrochemical double-layer capacitance (C dl ) to reflect the electrochemical active area (ECSA).…”

Partially exposed RuP 2 surface in hybrid structure endows its bifunctionality for hydrazine oxidation and hydrogen evolution catalysis

“…4C) to achieve 10 mA cm −2 , much lower than that of Pt/C (166 mV) and remarkable compared to those recently reported values (table S3). Excitingly, it can reach an ultralarge current density of 522 mA cm −2 at a cell voltage of 1.0 V, superior among the recent literatures on the energy-saving H 2 production systems (32,33). Besides, the comparing polarization curves (Fig.…”

Puffing quaternary FexCoyNi1-x-yP nanoarray via kinetically controlled alkaline etching for robust overall water splitting

“…Considering the same crystalline phases of FeCoNiP-PNAs and FeCoNiP-NWAs (Fig. S9), the puffed geometrical structure of FeCoNiP-PNAs with porosity, cavity and lattice defects derived from the kinetically controlled alkaline etching procedure can ensure adequate exposure and utilization of active sites in HER and OER [22]. Taken together, the simultaneous and elaborate manipulation of electronic and morphological structure in FeCoNiP-PNAs is responsible for the noticeable improvement in both HER and OER activities.…”

“…[20]. The loss of metal cations from the pristine FeCoNi NWAs may result in the formation of numerous defects in the FeCoNi-PNAs, thereby leading to more exposed active sites and promoted electrocatalytic performance [22]. The comparison of XPS results (Fig.…”