Dual Graphitic‐N Doping in a Six‐Membered C‐Ring of Graphene‐Analogous Particles Enables an Efficient Electrocatalyst for the Hydrogen Evolution Reaction

Abstract

Graphene‐based materials still exhibit poor electrocatalytic activities for the hydrogen evolution reaction (HER) although they are considered to be the most promising electrocatalysts. We fabricated a graphene‐analogous material displaying exceptional activity towards the HER under acidic conditions with an overpotential (57 mV at 10 mA cm−2) and Tafel slope (44.6 mV dec−1) superior to previously reported graphene‐based materials, and even comparable to the state‐of‐the art Pt/C catalyst. X‐ray absorption near‐edge structure (XANES) and solid‐state NMR studies reveal that the distinct feature of its structure is dual graphitic‐N doping in a six‐membered carbon ring. Density functional theory (DFT) calculations show that the unique doped structure is beneficial for the activation of C−H bonds and to make the carbon atom bonded to two graphitic N atoms an active site for the HER.

High Spatial Resolution Electrochemical Microscopic Observation of Enhanced Charging under Bias at Active Sites of N-rGO

“…In this study, non-faradic and faradic currents from the total currents in the SECCM image are isolated to realize the mapping of charge accumulation and electrochemical activity with a ∼135 nm resolution, as illustrated in Figure . N-doped graphene (N-rGO) is chosen as the model, which has excellent performance at electrical conductivity and stability. − The introduction of pyridine N (PD-N), pyrrole N (PR-N), and quaternary N (QN-N) in N-rGO has been reported to increase the HER activity to different extents. , Especially, PR-N and PD-N tend to be present at the edge of rGO, while QN-N is present at the surface of rGO. Therefore, it should be a good spatially resolved model to establish the correlation between the charge accumulation and the resultant electrochemical activity under the bias.…”

“…N-doped graphene (N-rGO) is chosen as the model, which has excellent performance at electrical conductivity and stability. 22 quaternary N (QN-N) in N-rGO has been reported to increase the HER activity to different extents. 25,26 Especially, PR-N and PD-N tend to be present at the edge of rGO, while QN-N is present at the surface of rGO.…”

Flame‐Assisted Synthesis of O‐Coordinated Single‐Atom Catalysts for Efficient Electrocatalytic Oxygen Reduction and Hydrogen Evolution Reaction

“…[ 9,21 ] In this architecture, heteroatom can not only effectively stabilize metal atoms but also modulate their electronic structures to optimize the adsorption/desorption of intermediates and thus enhance their electrocatalytic performances. [ 22–24 ] Although with important advances, efficient doping of other heteroatoms (except for nitrogen atoms) on carbon supports and the subsequent anchoring of metal atoms remain elusive and need further investigation.…”

Metal–Organic Frameworks‐Derived Self‐Supported Carbon‐Based Composites for Electrocatalytic Water Splitting

“…For the past few years, owing to the enhanced conductivity and good selectivity, non‐metallic heteroatom‐doped carbon nanomaterials‐based electrocatalysts have exhibited great potential for the development of water electrolysis [106–114] . N‐doped carbon‐based nanomaterials have attracted more attention, and the intrinsic electronic properties can be attributed to the conjugation between π‐system of C and lone pair electrons of N. The universal preparation strategies of MOFs‐derived self‐supported N‐doped carbon materials include two types.…”

“…For the past few years, owing to the enhanced conductivity and good selectivity, non-metallic heteroatom-doped carbon nanomaterials-based electrocatalysts have exhibited great potential for the development of water electrolysis. [106][107][108][109][110][111][112][113][114] N-doped carbon-based nanomaterials have attracted more attention, and the intrinsic electronic properties can be attributed to the conjugation between π-system of C and lone pair electrons of N. The universal preparation strategies of MOFs-derived selfsupported N-doped carbon materials include two types. (i) Insitu N-doping: N-containing ligands such as 2-methylimidazole, bipyridine, porphyrin, etc., are used to construct self-supported MOF precursors on conductive substrates, and these MOF precursors are directly carbonized to obtain self-supported Ndoped carbon materials in the inert gas atmosphere; [115][116][117][118][119] (ii) post-synthetic modification: self-supported N-doped carbon materials are prepared by direct carbonization of MOF precursors with N-rich guest molecules (e. g., NH 3 , urea, CH 3 CN).…”