Carbon Nanofiber Synthesis within 3-Dimensional Sintered Nickel Microfibrous Matrices: Optimization of Synthesis Conditions

Table 1

Sequence of CNF synthesis optimization efforts on nickel foil substrates.

Phases		Experimental details^*				Results
Phase number	Description of phase	Substrate pretreatment	H2	NH3	T	Raman	Carbon yield	Supporting SEM (figure number)
			(%)	(%)	(^°C)	(D/G ratio) (±0.02)	(mg C/g Ni foil) (±6%)
1	Effects of substrate pretreatment	As-received	10	0	470	0.96	10	4A and 5A
		Reduction at 715^°C for 15 min				1.06	16	4B and 5B
		Reduction at 815^°C for 120 min				1.04	17	4C and 5C
		Thermal faceting at 515^°C				1.06	21	4D and 5D
		Thermal faceting at 715^°C				1.07	69	4E and 5E
		Thermal faceting at 815°C				1.14	82	4F and 5F
2	Effects of CNF synthesis temperature (following Phase 1)	Thermal faceting at 815^°C	10	0	420	—	3	6A
					470	1.14	82	6B
					520	1.19	102	6C
					570	1.31	44	6D
					670	0.93	2	6E
					770	—	8	6F
3A	Effects of hydrogen concentration (following Phase 2)	Thermal faceting at 815^°C	0	0	520	—	5	—
			10			1.19	102	—
			30			0.97	136	—
			98			0.84	150	—
3B	Verify optimal CNF synthesis temperature (following Phase 3A)	Thermal faceting at 815^°C	98	0	420	—	0	—
					470	0.75	17	7A
					520	0.84	150	7B
					570	0.9	179	7C
					620	1.11	177	7D
					670	1.49	108	7E
					720	—	3	7F
					770	—	0	—
3C	Verify effects of substrate pretreatment (following Phase 3A)	Reduction at 715^°C for 15 min	98	0	420	—	0	—
					470	0.64	7	—
					520	0.82	48	—
					570	0.80	123	—
					620	0.97	51	—
					670	1.15	36	—
					720	—	3	—
					770	—	3	—
4A	Effects of ammonia concentration (following Phase 3B)	Thermal faceting at 815^˚C	98	0		0.9	179	8A
			78	20		0.92	164	8B
			48	50	570	1	154	8C
			18	80		0.99	36	8D
			0	98		—	1	8E
4B	Verify 570^°C is optimal CNF synthesis temperature (following Phase 4A)	Thermal faceting at 815^°C	78	20	520	0.77	130	9A
					570	0.92	164	9B
					620	1.14	162	9C
					670	—	9	—
					720	—	2	—
					770	—	4	—
					820	—	3	—
					870	—	2	—
					920	—	3	—
4C	Verify effects of substrate pretreatment (following Phase 4A)	Reduction at 715^°C for 15 min	78	20	570	—	68	10A
		Thermal faceting at 815^°C				0.92	164	10B.1
		—				—	—	—

^∗Nitrogen used as inert diluent and 2% acetylene for CNF synthesis.