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[Display omitted] • A new graphdiyne based metal-free catalyst was successfully synthesized. • The catalyst triggered highly catalytic performances toward hydrogen evolution. • The unique nanostructure guaranteed the fast proton-electron transfer during HER. • The alkyne-alkene transition induced the excellent catalytic activity of TAGDY. Graphdiyne-based metal-free catalysts demonstrate outstanding performances in electrocatalysis. In order to accurately understand the activity origin of metal-free electrocatalytic hydrogen production at the atomic level, we have successfully designed and prepared a new metal-free catalyst of 1,2,4-triamino-graphdiyne (TAGDY). Structural characterizations showed that TAGDY has unique nanostructure, which guarantees the fast proton-electron transfer during the catalytic process. Experimental studies revealed that TAGDY possesses excellent electrocatalytic activities and long-term durability towards hydrogen evolution in acidic conditions, better than the most reported metal-free electrocatalysts. Density functional theory calculations and Born-Oppenheimer molecular dynamics simulations revealed that the interaction of (H++e−) pair with alkyne bond induces the transition between C C and C C in TAGDY, which effectively enhanced the catalytic activities of initial inert carbon sites. Combination of theory and experiment as well as the structural characterization, a new level of knowledge for the activity origin and catalytic mechanism of graphdiyne-based metal-free electrocatalysts are presented. [ABSTRACT FROM AUTHOR]

The carbon dioxide (dry) reforming of methane (DRM) (CH 4  + CO 2  → 2CO + 2H 2 ) on La and La 2 O 3 modified Ni(1 1 1) has been investigated theoretically. As promoters, La and La 2 O 3 strengthen the adsorption of the intermediates compared with pure Ni(1 1 1). The strong adsorption of CO 2 on La 2 O 3 modified Ni(1 1 1) deforms La 2 O 3 , and the complex intermediate CO 2 (La 2 O 2 -O) is formed. The CO 2 (La 2 O 2 -O) participates in the DRM reaction and reduces the carbon deposition on the catalyst surface. For La and La 2 O 3 modified Ni(1 1 1), the reactions of CH 4  + CO 2  → CH + 3H + CO + O → CHO + 3H + CO → 2CO + 2H 2 and CH 4  + CO 2  + La 2 O 3  → CH + CO 2 (La 2 O 2 -O) + 3H → CHO + CO 2 (La 2 O 2 ) + 3H → 2CO + 2H 2  + La 2 O 3 are the most favorable pathways for DRM, respectively. Both the density functional study and microkinetic analysis support that compared with pure Ni(1 1 1), La and La 2 O 3 modified Ni(1 1 1) improve the reaction both thermodynamically and kinetically. The carbon deposition is suppressed on La 2 O 3 modified Ni(1 1 1) due to the lower rate in the reaction CH → C + H, compared with La modified Ni(1 1 1). [ABSTRACT FROM AUTHOR]